JCL QUESTIONS AND ANSWERS
1.1. EXCEPTION HANDLING
Q: What is an Operation Exception error?
A: An Operation exception error indicates that an operation code is not assigned or the assigned operations not available on a particular computer model. The machine does not recognize the instruction or operation used. A possible reasons a subscript error. This error could also be caused by an attempt to read a file that was not opened, a misspelled DD statement.
A: An addressing exception error occurs when a program is attempting to access a memory location, which is outside the bounds of a available real storage on the machine.
This can be caused by a dataset not being open end at the time an I/O was directed to it, an attempt to close a dataset a second time, incorrectly called module parameters or coding, improper exit from a performed paragraph, or uninitialized subscript or index. The system completion code is 0C5.
Q: What is a data exception?
A: A data exception error indicates an attempt to perform an arithmetic operation on non-numeric data. It can also occur from incorrect input data to a program that is not performing sufficient numeric testing on it before attempting arithmetic. The system completion code is 0C7.
Q: What return code is issued when a operator cancels a job?
A: There are two return codes, which can be produced when the operator cancels a job. They are 122 and 222. A 122 indicates the operator cancelled the job and requested a dump. A222 indicates the operator has cancelled the job and has not requested a dump.
It is important to ask the operator why the job was canceled. Some of the reasons this may occur are: the program appeared to be stalled in a wait state; or the program was in an apparent loop.
Q: What return code is issued if a job step exceeded the time limit?
A: The system will issue a system code of 322 when a job or job step has exceeded the time limit .If the time parameter was used on the JOB or EXEC statement. If the time parameter was not used, then it is important to check the program possible errors.
Q: When the system cannot find enough virtual storage, which system abend is issued?
A: When the system cannot find enough virtual storage during a GETMAIN macroinstruction, it generates a system abend of 804 or 80A. Check for program errors that incorrectly modify the storage request. If the REGION parameter has been used, either on the JOB or EXEC statement, it may need to be increased to satisfy the request.
Q: Which system completion code is issued when a program module cannot be found?
A: A system completion code of 806 will be issued when a program module cannot be found. Some of the causes may be missing the STEPLIB statement from the step or missing the JOBLIB statement from the job stream. Most likely the program name was misspelled on the EXEC statement or in a source code CALL.
Q: What are some of the abend generated when not enough disk space is available and what do they mean?
A: Some of the abend generated due to a lack of available disk space are:
B37 -- Disk volume out of space, cannot write output. The system gave all the primary space and as much secondary space as it could.
D37 -- Primary disk space was exceeded and either no secondary space allocation was specified or it was insufficient. One should increase the primary space as well as provide adequate secondary allocation was specified or it was insufficient. One should increase the primary space as well as provide adequate secondary space allocation to eliminate this error.
E37 -- There was insufficient space on the volume. One way to solve this problem is to specify more volumes on the JCL.
Q: Which abend is issued when the system cannot find a member on a portioned dataset?
A: An S013-18 abend occurs when the specified member on the JCL, is not found on the indicated PDS (Partioned Dataset). Determine if the member is spelled correctly on your JCL. If it is not, then fix member name and resubmit job. If it is correct, then determine why it is not on the PDS, take the necessary steps to place it on the PDS, and resubmit the job.
Q: What normally causes an S013-20 abend?
A: An S013-20 is normally caused by the block size not being a multiple of the record length or being incorrect for variable-length records. Divide your BLKSIZE by the record length to make sure it is a multiple of the BLKSIZE if not, correct it and resubmit job. For variable-length records, it is necessary to have your BLKSIZE be at least 4 bytes greater than your record length.
Q: What can be done to eliminate a ‘NOT CATLG 2’ for a particular dataset?
A: To eliminate a ‘NOT CATLG 2’ message, one may take one of the following options.
Add a step to the beginning of the JOB, which creates the dataset to first purge the dataset. One may to use utility IEFBR14 to perform this task.
Setup a job to purge the dataset and run it before the job which creates it purges the dataset before running the job, which creates it.
Q: If a job step is in a wait state for 30 minutes or more with no activity, which abend does one receive?
A: If a job step is in a wait for 30 minutes or more with no activity, the job abend with an s522 indicating the time was exceeded for the wait state. This type of cancellation is unusual and is often caused by a program error or unavailable datasets / resources.
Q: A system completion code of 813-04 is generated when a dataset name and volume serial number for a tape is not consistent with the information contained in the tape dataset label. What can be done to fix this problem?
A: When a system completion code of 813-04 is received, one must check the spelling of the dataset name in the JCL and the volume serial number specified. If possible, dump the dataset label to see the actual dataset name on the tape. Once the problem has been identified, correct it and resubmit the job.
Q: How does one fix a ‘PROCEDURE NOT FOUND ‘ ERROR?
A: If one receives a ‘procedure not found’ message, it indicates that it could not find the procedure on the procedure library specified on the JCL. Check the spelling of the procedure library specified on the JCL.
Check the spelling of the procedure name on the EXEC statement to make sure it is correct .if it is not correct, fix it and resubmit the job.
If the JCL is correct, then check to make sure the procedure has been cataloged into the procedure library. If not, have it cataloged and resubmit the job.
1.2. GENERATION DATA GROUPS
Q: What is a Generation Data Group (GDG)?
A: A generation Data Group is a group of chronologically or functionally related datasets. GDGs are processed periodically, often by adding a new generation, retaining previous generations, and sometimes discarding the oldest generation.
Q: How is GDG base created?
A: A GDG base is created in the system catalog and keeps track of the generation numbers used for datasets in the group. IDCAMS utility is used to define the GDG base for MVS/XA, and MVS/ESA. Older systems required that the IEHPROGM utility be used.
Q: What is model dataset label (Model DSCB)?
A: A model dataset label is a pattern for the dataset label created for any dataset named as part of the GDG group. The system needs an existing dataset to serve as a model to supply the DCB parameters for the generation data group one wish to create. The model dataset label must be cataloged. The model DSCB name is placed on the DCB parameter on the DD statement that creates the generation data group.
Q: What is the advantage in using generation data groups?
A: The advantage in using the generation data groups is that all datasets have the name, and the system keeps track of adding and deleting successive generations. The JCL does not need to be changed between runs.
Q: How are GDG concatenated?
A: Generation data groups are concatenated by specifying each dataset name and the generation number of all generations of the generation data group . To retrieve all generations of a generation data group, omit the generation number. The DD statements refers to all generations
The result is the same as if all individual datasets were concatenated. If generations are not on the same volume, this will not work.
Q: How are different generations specified?
A: Different generations are specified by providing the dataset name and generation number for each GDG desired.
Q: What is the status of the GDG when an abend occurs?
A: The GDG is in a bad state because it may consist of partial information. If used in this state, it is possible to get incorrect or improper results. It is recommended to reset the current generation by deleting the bad generation before executing the job, which will re-create a new generation.
Q: How is a previous GDG coded?
A: Previous GDGs are coded as (-1) after the dataset name. An example would be DSN=JAN.DATA(-1).
Q: How is the current GDG coded?
A: Current GDGs are coded as (0), (+0), or (-0) after the dataset name as follows: DSN=JAN.DATA(0). The +(0) and (-0) have the same effect as (0) Normally, it is coded as (0).
Q: How is a new GDG coded?
A: A new GG is coded as (+1) after the dataset name as follows:
DSN=JAN.DATA(+1). This will cause all generations to be pushed down one level at the end of the job.
1.3. DD STATEMENTS
Q: What is the purpose of the Data Definition (DD) Statement?
A: Data Definition statements describe each dataset (a file on a direct-access storage device, tape or printed output) and request the allocation of I/O devices.
Q: Describe what the DISP parameter does?
A: The DISP parameter describes the current status of the dataset and directs the system
on the disposition of the dataset either at the end of the job or when the step abnormally terminates . DISP always required unless the dataset is created and deleted in the same step
Q: How many subparameters does the DISP parameter consist of and what is the meaning of each?
A: The DISP parameter consists of three subparameters: start-status, end-status-normal and end-status-abend. Start-status indicates the status of a dataset at the beginning of the job step. End-status-normal tells MVS what needs to be done with the dataset when the job step ends. End-status-abend indicates the desired disposition of the dataset if the job step abend. It is also known as the conditional disposition.
Q: What are the meanings of the parameters used (within) the DISP parameter at the beginning of the job step?
A: The status NEW, MOD, OLD, or SHR is the status of the dataset at the beginning of the step. If the dataset is NEW, the system creates a dataset label; if it is OLD, the system locates the dataset. The system gives a program exclusive control of a database except when SHR is used.
Q: What are the normal “disposition” of the DISP parameter?
A: The normal disposition indicates the disposition of the dataset when the dataset is closed or when the job terminates normally. Normal dispositions are KEEP, DELETE, PASS, CATLG, and UNCATLG.
Q: What is the abnormal “disposition” of the DISP parameter?
A: The abnormal disposition would be effected only if the step abnormally terminates. They are the same normal disposition as except that PASS is not allowed KEEP, CATLG, UNCATLG and DELETE are all permitted.
Q: When should DISP=SHR be used?
A: DISP=SHR must be used only when it is necessary to share the dataset.
SHR should b used for input dataset.
Q: When should DISP=MOD be used?
A: DISP=MOD is used to either to extend an existing sequential dataset or to create a dataset if it does not exist. If the dataset exists the records are appended at the end of the existing dataset. If the dataset does not exist the system treats mod as if it were NEW, provided that the volume parameter has not been used. If the volume parameter is used, the system terminates the job and does not create the new dataset. MOD can be used to add to the dataset that extends to several volumes. Always specify a disposition of CTLG with the MOD for cataloged dataset, even if they are already cataloged, so that any additional volume serial number will be recorded in the catalog.
Q: When should DISP = OLD be used?
A: DISP = OLD should be used for an existing dataset. It can be used with an input dataset to read or an output dataset to rewrite. The step which uses DISP=OLD will have exclusive control of the dataset. If an OLD dataset is cataloged, the DSN parameter is usually the only other parameter needed. If an LD dataset is not cataloged, UNIT and VOL parameter are required.
Q: When should DISP = NEW be used?
A: DISP=NEW should be used when it is desired to create a dew dataset. The UNIT parameter is usually required for dataset on direct access volumes.
Q: How is a dataset passed from one step to another?
A: A dataset is passed from one step to another based on what is coded on the DISP parameter. The dataset can only be passed to subsequent steps if PASS is used on the disposition parameter.
Q: If a dataset is passed and the subsequent steps do not use it, what happen to the dataset at the end of the job?
A: If a dataset is passed to subsequent steps and it is not used, at the end of the job the dataset is deleted, since DELETE is assumed for all NEW datasets, temporary or non temporary.
Q: What is the default for the disposition parameter if it’s not coded on the DD statement for a dataset?
A: The default disposition used on a dataset, which was coded without a disposition parameter, is NEW. The disposition of NEW implies exclusive control of the dataset.
Q: How are dataset concatenated?
A: Datasets are concatenated by writing a normal DD statement for the first dataset and the adding a DD statement without a DDNAME for each dataset to be concatenated in the order they are to be read. The following is an example of three datasets concatenated:
//INSMP DD DSN=JAN.DATA, DISP=SHR
// DD DSN=FEB.DATA, DISP=SHR
// DD DSN=MAR.DATA, DISP=SHR
Q: Can datasets of a different record length (LRECL) be concatenated?
A: Datasets with different LRECLs can be concatenated as long as the dataset with the largest block size appears first.
Q: Can Partitioned Datasets (PDSs) be concatenated?
A: Partitioned Datasets can be concatenated. This is often done for program libraries so that the system can search several libraries fro a member.
Q: What is a Data Control Block (DCB)?
A: The Data Control Block is a table of data, in storage, that describes each dataset used by the program.
Q: What are two different places from which DCB information can be obtained and in what order?
A: Data information can be obtained from three places in the following order:
The data control block, from application program, is used first.
Information supplied on the DD statement is used second.
Dataset label information for the DCB is used third.
Q: What is the purpose of using a dataset referback?
A: A dataset referback is used to copy a dataset name from a prior job step.
Q: What are the disadvantages of using a dataset referback?
A: The disadvantages of using dataset referback is that they tend to make JCL more difficult to maintain because close attention, scrutiny and manual examination of preceding steps is needed to understand what a given job-stream is doing. They also complicate the restart of a job if a failure or interruption occurs.
Q: Under which circumstances is the disposition parameter not performed?
A: Disposition is not performed under the following circumstances:
The step does not start because of JCL errors.
The step is bypassed because of the COND parameter in the JOB or EXEC statement
The step abnormally terminates because it could not find enough space to satisfy the request.
DUMMY or DSN=NULLFILE is coded on the DD statement.
1.4. JOB, EXEC, AND PARM
Q: What is the purpose of the JOB statement?
A: The purpose of the JOB statement is to inform the operating system of the start of a job, give necessary accounting information and supply run parameters. Each job must begin with a single JOB statement.
Q: How does one identify a job to the Operating system?
A: A job is identified to the system by the use of jobname. Jobnames can range from one to eight alphabetic characters. The first character must begin in column 3 and be alphabetic (A-Z). Jobs should be given unique names since duplicate jobnames will not execute until any job having the same jobname completes execution.
Q: What does the accounting information consist of?
A: Accounting information consists of the account number of which the job is charged and any additional information established by the installation.
Q: What does the parameter CLASS in the JOB statement mean?
A: Parameter CLASS specifies the job class. There are 36 possible job classes (A-Z, 0-9). Installations usually attempt to establish job classes that achieve a balance between I/O bound and CPU-bound jobs. Job classes also determine the overall priority of a job, along with the PRTY parameter PRTY may be coded to give special priority to a job. The operator may also set it.
Q: What is parameter MSGCLASS in the JOB statement used for?
A: The MSGCLASS parameter is used to specify the job scheduler message output class. The output classis (A-Z,0-9). Job scheduler message include all messages not printed by the actual job steps being executed. Some of these are: JCL statements and error messages, device allocations, dataset disposition and accounting information.
Q: What does parameter MSGLEVEL on the JOB statement mean and what is the advantage of using it.
A: MSGLEVEL indicates whether or not one wishes to print the JCL statements and allocation messages. The MSGLEVEL parameter can save paper. After a job is debugged, there may be no need to print all the JCL and allocation messages each time it runs. To reduce printing to a minimum one may wish to code MSGLEVEL = (0,0)
Q: which parameter allows one to run a syntax check n the JCL without executing it?
A: TYPRUN = SCAN parameter is used to check the JCL for syntax errors and suppress the execution of the job. This checking does not include checking for duplicate datasets on volumes, insufficient space or region size for job steps.
Q: What does parameter TYPRUN = HOLD mean?
A: The parameter TYPRUN = HOLD holds a job in the input queue for later execution. The job is held until the operator releases it. TYPRUN=HOLD is useful for when one job must not run until another job completes. Operator intervention is required to release the job.
Q: What is the purpose of the EXEC statement?
A: The purpose of the EXEC statement is to name a program or procedure to be executed. It follows the job statement. A job or cataloged procedure can contain several EXEC statements. A job may have up to 255 EXEC statements.
Q: What is the stepname on the EXEC statement used for and is it a required parameter?
A: Stepname on the EXEC statement is used to name the job step. It is required if subsequent JCL statements refer to it or if one wishes to restart the job from the step; otherwise it is optional. Stepname are recommended and should have unique names. The names must begin in column 3 with an alphabetic or national character (A-Z, @$#)
Q: Which parameter is used to name the program in the exec statement?
A: The parameter ‘PGM=’ is used to name a program or utility to be executed. For example, to code a program named ‘FIRST’, one would code ‘PGM=FIRST’. For utility named ‘IEBGENER’, it would be coded as ‘PGM=IEBGENER’.
Q: What are the commonly used parameters on the EXEC statement and what do you they mean?
A: The most commonly used parameters on the EXEC statement are: COND, PARM, REGION, and TIME. They stands for:
1. COND – Specifies conditions to execute subsequent job steps if the previous step(s) fail.
2. PARM – Passes parameter to the job steps.
3. REGION – Specifies the region size to allocate for the job / job step.
4. TIME – Imposes a time limit on the job or job step.
Q: What is the default for the TIME parameter if it is not coded on the EXEC statement?
A: If the TIME parameter is omitted from the EXEC statement, the default is 30 minutes of the CPU time.
Q: What is the difference between the JOBLIB & STEPLIB statements?
A: The JOBLIB statement is placed after the JOB statement and is effective for all job steps. It cannot be placed in the catalogued procedure. The STEPLIB statement is placed after the EXEC statement and is effective for that job step only. Unlike JOBLIB statement, the STEPLIB cannot be placed in the catalogued procedure.
Q: What can be done to resolve a JCL error that reads ‘DATASET NOT FOUND’?
A: Some of the actions one can take to resolve a JCL error ‘DATASET NOT FOUND’ are:
1. One must examine the job log and the allocation/deallocation report and identify the step and DDname involved.
2. Determine whether or not the dataset name does indeed exist on the system.
3. Check the JCL to make sure the dataset name is spelled correctly.
4. If the job has more than one step and the ABEND is not on the first step, check to see if the dataset on the previous step was deleted.
5. Fix the problem and resubmit the job.
Q: Does a ‘DD STATEMENT MISSING’ message normally ABEND the job?
A: A DD statement missing message normally does not ABEND the job, but if not fixed it could later cause problems when least expected. It is advisable to determine why this message was generated and take action to rectify the problem.
Q: Parameters COND, REGION, AND TIME can be coded on both the JOB and the EXEC statements. What are the differences between using them on the JOB versus the EXEC statements, and in which statements are they commonly used?
A: Parameters COND, REGION, AND TIME coded on the JOB statement will be in effect for the entire job. When used on the EXEC statement, they will be in effect for that job step only. The COND parameter is normally used on the EXEC statement. The REGION parameter is not normally used unless a particular program requires a lot of storage and it is necessary to override the installation’s REGION Default. If the REGION parameter is used on the both JOB
and EXEC statements, then the REGION parameter from the JOB statement will be in effect. The TIME parameter is most often used on the JOB statement.
Q: Explain how the virtual storage works in MVS/SP.
A: MVS/SP stands for Multiple Virtual Storage / System Program. A major architectural component of virtual storage MVS is virtual storage. With virtual storage, storage addresses of the application program are independent of the addresses of the computers central storage. A Hardware feature, paging supervisor, transfers the users virtual storage addresses to the computers central storage addresses during execution. With Virtual Storage, a program needs to occupy only a relatively small amount of central storage. This allows programs to be run whose size exceeds the central storage available on the computer.
Q: What are some of the main features of MVS/XA?
A: MVS/XA stands for Multiple Virtual Storage / Extended Architecture. MVS/XA uses 32 bits of addressing. This gives an address space of approximately 2 billion bytes. The extended architecture also consists of more sophisticated I/O channels for faster I/O. Also, a separate version of OS is required. One of the difference is that a program for MVS/XA can go up to 2 billion bytes. Programs running under MVS/SP can go up to
16 million bytes.
Q: What are the “basic architecture” features of MVS/ESA?
A: MVS/ESA stands for Multiple Virtual Storage / Enterprises System Architecture. MVS/ESA permits an application to have multiple 2-gigabyte address spaces. This allows huge applications to be segregated into functional parts. For ESA, the first address space is called the application space and programs can execute in it. The other address space are called dataspaces and they contain only data. MVS/ESA also has the facility for hyperspaces, which allows temporary data to be stored or retrieved in 4-kbyte blocks under program control. Maximum address space is up to 2 trillion bytes in multiple of 2-billion-byte address spaces.
Q: What is the meaning of the “line”?
A: The “line” indicates the maximum address space that is available for the MVS system. For MVS/SP it is 16 million bytes, for MVS/XA it is up to 2 billion bytes, and MVS/ESA is up to 2 trillion bytes in multiple of 2-billion-byte address spaces.
Q: When would a program run “below the line”?
A: A program would run “below the line” if it did not exceed the address space available.
Q: When would a program run “above the line”?
A: A program would run “above the line” if it required more than 16 megs or if it is competing with other programs which are using the same address space. Special Parameters must be set for compilation and linkage editing in order for a program to run above the 16-meg line.
Q: How are in-stream procedures (procs) built?
A: In-stream procedures are built by coding a set of statements and placing them after the JOB statement and before the EXEC statement. In-stream procedures begin with a PROC statement and end with a PEND statement. Up to 15 in-stream procedures can be included in a single job.
Each in-stream procedures may be invoked several times within the job. In-stream procedures can use symbolic parameters in the same way as catalogued procedures.
Q: What is the difference between an in-stream procedure and a catalogued procedure?
A: An In-stream procedure is basically same as a catalogued procedure. The difference is that to execute an in-stream procedure one places it after the JOB statement and before the EXEC statement and must end it with a PEND statement. A catalogued procedure is catalogued on a procedure library and is called by specifying the procedure name on the EXEC statement. An in-stream procedure is useful to test the procedure before making it a catalogued procedure.
Q: Name some of the JCL statements that are not allowed in the procs.
A: Some of the JCL statements that are not allowed in the procs are:
1. JOB Delimiter (/*) or Null (//) statements
2. JOBLIB or JOBCAT DD statements
3. DD * or DATA statements
4. Any JES2 or JES3 control statements
Q: What parameters are good candidates to make symbolic parameters?
A: Any parameter, sub parameter, or value in a procedure that may vary each time the procedure is called is a good candidate to be coded as a symbolic parameter.
Q: Which type of override parameter requires that one know the parameters that can be overridden?
A: Regular parameters require that one know the parameters that can be overridden, such as step names within the procedure, the DDnames of the statements overridden, and the order of the DD statements.
Q: How is a symbolic parameter coded?
A: A symbolic parameter is preceded by an ampersand (&) and followed by a name (&FIRST). The first character must be alphabetic. Symbolic parameters can be coded only in the operand field of the JCL statements; they cannot appear in the name or operation field of the JCL statements. If more than one value is assigned to the symbolic parameters on a PROC or EXEC statement, only the first one is used. Symbolic parameters may be coded in any order on the PROC or EXEC statement.
Q: How are values assigned to symbolic parameter?
A: Values can be assigned to symbolic parameter on the PROC statement, on the EXEC statement, or on a SET command. Values containing special characters other than blank must be enclosed in apostrophes. The Values assigned to symbolic parameter can be of any length, but it cannot be continued onto another line.
Q: Can symbolic parameter concatenated?
A: Symbolic parameter can be concatenated with other symbolic parameters, regular parameter or with the portions of the regular parameters as follows
Symbolic/symbolic – PARM-&FIRST&LAST
Symbolic/regular – SPACE-&SPACES
Symbolic/portion – SPACE-CTRK, &PRIMARY
Q: What are some of the rules involved in overriding parameters on the EXEC statements in a procedure?
A: To override EXEC parameter one should follow these rules
1. A PGM parameter cannot be overridden.
2. The parameter for each step do not need to be coded in the same order as they appear on the procedure EXEC statement
3. To add or override a parameter on an EXEC statement, code it as follows parameter.procstepname=value.
4. If a parameter which does not exist is coded on the EXEC statement, the parameter will be added
5. All parameters in each step must be coded in order: the first step must be coded first, second step second, third step third, etc.
Q: What are some of the rules involved in overriding DD statements in procs?
A: The following rules apply when overriding a DD statement:
1. DD statement overrides precede the DDname with procstepname
2. The JCL parameter is replaced unless it does not exist on the original statement, in which case it is added. For the DCB each sub parameter can be overridden
3. DD statement overrides should carry DDnames that already exist in the step they are to effect
4. DD statement overrides must be coded preceding any added DD statement for the proc step
5. DD override statement must be listed in the order in which they are shown in the proc
6. DD override statement are only in effect for the duration of the run
Q: How are concatenated DD statements in the proc overridden?
A: Overriding concatenated DD statements requires the following:
1. To override only the first DD statement in a concatenation, code only one overriding DD statement
2. To override all DD statements in a concatenation, code an overriding DD fo each concatenated DD statement
3. The overriding concatenated DD statements must be in the same order as the concatenated DD statement
4. Code a DDname on the first overriding DD statements only. Leave the DDname blank on the following DD statements.
5. To leave a concatenated statements unchanged, code its corresponding, overriding DD statement with a blank operand field
1.6. COMPILING, LINK EDITING AND EXECUTION
Q: What does a mainframe compiler output in the object deck and what does the linkage editor do with it?
A: The compiler outputs the source code into the object deck in a form to be read by the linkage editor. The linkage editor combines the object dataset (object deck) from the compiler with machine language code for input/output and other tasks to create an executable load module.
Q: If a program executed attempts to divide a number by zero, do arithmetic on a field that does not contain numeric data, or has some other serious logic error, an abend will occur. What is the normal response that MVS would issue?
A: MVS would issue a “system completion code” that would indicate the nature of the problem, dump the program’s memory area, and flush the job from the system. The dump may be used for problem analysis. The dump is printed or stored in a dataset as specified in the //SYSUDUMP DD statement. If //SYSUDUMP is omitted, MVS will provide the completion code value, but not the dump.
Q: Where must load module(s) reside?
A: Load module(s) must reside on a Partitioned DataSet (PDS).
Q What are some of the common linkage editor options and what do they mean?
A: Some of the commonly used linkage editor options are
1. LIST – Lists the linkage editor control statements and is usually specified. Omit the parameter if no linking is declared.
2. MAP – Produces a storage map showing the length and relative locations of all control sections. Default is NOMAP.
3. XREF – Includes MAP plus a cross-reference table of the load module (MAP and XREF are mutually exclusive)
4. NOCALL - Cancels the automatic library call mechanism. NOCALL is used for creating subroutine libraries so that the load module contains a single subroutine. CALL is the default.
5. LET – Marks load modules as executable even if minor errors are found. NOLET is the default.
6. PRINT – Allows the messages to be written to a SYSOUT DD statement and it is the default. NOPRINT suppresses the message.
7. AMODE – Specifies whether the program uses 24 or 31- bit addressing. AMODE ANY specifies both 24 and 31 – bit addressing. AMODE 24 requires the program to run below the 16-meg line. The default is established by the compiler and is usually AMODE 24.
8. RMODE – Indicates where the program can reside in virtual storage. RMODE ANY allows the program to reside above the 16-meg line and requires AMODE 31 or AMODE ANY. RMODE 24 requires the program to reside below the 16-meg line. The default is established by the compiler and is usually RMODE 24.
9. TERM – Causes linkage editor diagnostic message to be written to a SYSTERM DD statement. NOTERM is the default.
Q: What causes the message ‘MODULE HAS BEEN MARKED NOT
A: An unresolved external reference often causes the message ‘MODULE HAS BEEN MARKED NOT EXECUTABLE’. Although the module is not executable, one may be able to recover by link-editing the control section causing the problem and replacing it in the load module.
Q: Why would the linkage editor add a member to a load library under the name ‘TEMPNAME’?
A: The linkage editor will add a member to the load library under the name of ‘TEMPNAME’ when a member of the same name already exist on the library and the disposition on the SYSLMOD statement was coded as DISP = MOD. This indicates a problem and need s to be resolved.
Q: What is an IEBGENER used for?
A: IEBGENER is a dataset utility used to copy sequential datasets, produce a partitioned dataset or member from a sequential dataset, produce an edited sequential or partitioned dataset, and reblock / change the logical record length of a dataset.
Q: What is an IEBCOPY used for?
A: IEBCOPY is a dataset utility used to copy one or more partitioned datasets or to merge partitioned datasets. A partitioned dataset that is copied to a sequential dataset is said to be unloaded. When one or more dataset created by an unload operation are used to recreate a partitioned dataset, it is called a load operation. Specific members of a partitioned or unloaded dataset can be selected for, or excluded from, a copy, unload or load process.
Q: What is an IEFBR14 used for?
A: IEFBR14 is used to delete datasets, find dataset, catalog, and uncatalog datasets.
Q: What is an IEHLIST used for?
A: IEHLIST is a system utility used to list entries in an OS CVOL, entries in the directory of one or more partitioned datasets, or entries in an indexed or nonindexed volume table of contents (VTOC).
Q: What is an IEHINIT used for?
A: IEHINIT is a system utility used to write an IBM volume label onto any number of magnetic tapes mounted on one or more tape units. Each volume label set created by this program contains a standard volume label, and 80-byte dummy header and a tapemark.
Q: What is an IEBPTPCH used for?
A: IEBPTPCH is a dataset utility used to print or punch all or selected, portions of a sequential or partitioned dataset. Records can be printed or punched to meet either standard specifications or user specification.
Q: What is an IEBUPDTE used for?
A: IEBUPDTE is a dataset utility used to create and update dataset libraries, modify existing partitioned members or sequential dataset and change the organization of dataset from sequential to partitioned or Vice Versa.
Q: What utility can be both used for VSAM and NON VSAM files?
A: IDCAMS utility is used to handle VSAM and NON VSAM files.
Q: Which parameter is required to copy the dataset using IEBCOPY?
A: The parameter “COPY” is required to indicate one or more IEBCOPY copy, unload or load operations. Any number of operations can follow a single COPY statement and any number of COPY statements can appear within a single job step.
Q: What is the parameter ‘GENERATE‘ used for on utility IEBGENER?
A: The parameter ‘GENERATE’ for the utility IEBGENER is used when output is to be partitioned, editing is to be performed or user routines are provided and / or label processing is specified.
Q: What is the parameter ‘MEMBER’ used for an utility IEBGENER?
A: The parameter ‘MEMBER’ for the utility IEBGENR is used when the output is to be partitioned. One member statement must be included for each member to be created by IEBGENER. ALL RECORD statements following a MEMBER statement pertain to the number named in that MEMBER statement.
Q: What is the parameter ‘RECORD’ used for on utility IEBGENER?
A: The parameter ‘RECORD’ for the utility IEBGENER is used to define a record group and to supply editing information. A record group consists of records that are to be processed identically.
Q: Which utility uses the ‘REPRO’ command and what function does it perform?
A: The utility IDCAMS uses the ‘REPRO’ command. The REPRO command copies sequential datasets. It performs much the same function as IEBGENER.
Q: How does one verify that a utility has ended normally?
A: To verify if a utility has ended normally, one must check the JCL for a return code of zero. Various utilities generate return codes of 0004, 0008, 0012 and higher, in increments of 4, when problems or unusual conditions have been encountered.
Q: When a utility ends with a nonzero return code, what must be done to resolve the problem?
A: When a utility ends with a nonzero return code, it is necessary to determine what caused the error. One may start by checking for error message generated by the utility and look them upon on a utility messages manual. Also, the JCL statements and / or control statements should be checked to make sure they were properly coded. Once the error has been identified, it should be fixed and the job resubmitted.
Q: What are the kinds of job control statements?
A: The JOB, EXEC and DD statement.
Q: What is the meaning of keyword in JCL? What is its opposite?
A: A keyword in a JCL statement may appear in different places and is recognized by its name, e.g. MSGCLASS in the JOB statement. The opposite is positional words, where their meaning is based on their position in the statement, e.g. in the DISP keyword the =(NEW, CATLG, DELETE) meanings are based on first, second and third position.
Q: Describe the JOB statement, its meaning, syntax and significant keywords.
A: The JOB statement is the first in a JCL stream. Its format is // jobname, keyword JOB, accounting information in brackets and keywords, MSGCLASS, MSGLEVEL, NOTIFIY, CLASS, etc.
Q: Describe the EXEC statement, its meaning, syntax and keywords.
A: The EXEC statement identifies the program to be executed via a PGM=program name keyword. Its format is //jobname EXEC PGM=program name. The PARM= keyword can be used to pass external values to the executing program.
Q: Describe the DD statement, its meaning, syntax and keywords.
A: The DD statement links the external dataset name (DSN) to the DDNAME coded within the executing program. It links the file names within the program code to the file names know to the MVS operating system.
The syntax is // DDname DD DSN=dataset name. Other keywords after DSN are DISP, DCB, SPACE, etc.
Q: What is a PROC? What is the difference between an instream and a catalogued PROC?
A: PROC stands for procedure. It is 'canned' JCL invoked by a PROC statement. An instream PROC is presented within the JCL; a catalogued PROC is referenced from a proclib partitioned dataset.
Q: What is the difference between a symbolic and an override in executing a PROC?
A: A symbolic is a PROC placeholder; the value for the symbolic is supplied when the PROC is invoked, eg. &symbol=value. An override replaces the PROC's statement with another one; it substitutes for the entire statement.
Q: What is RESTART? How is it invoked?
A: RESTART is a JOB statement keyword. It is used to restart the job at a specified step rather than at the beginning.
Q: What is a GDG? How is it referenced? How is it defined? What is a MODELDSCB?
A: GDG stands for generation data group. It is a dataset with versions that can be referenced absolutely or relatively. It is defined by an IDCAMS define generation datagroup execution.
Q: Explain concatenating datasets.
A: Datasets can be grouped in a DD statement one after another, eg. in a JOBLIB statement where the load module can exist in one of many datasets.
Q: What is the difference between specifying DISP=OLD and DISP=SHR for a dataset?
A: DISP=OLD denotes exclusive control of the dataset; DISP=SHR means there is no exclusivity.
Q: What is MOD and when would you use it?
A: DISP=MOD is used when the dataset can be extended, ie, you can add records at the end of an existing dataset.
Q: What are the keywords associated with DCB? How can you specify DCB information? What is the OS precedence for obtaining that DCB information, ie. where does the system look for it first?
A: The keywords associated with the DCB parameter are LRECL, RECFM, BLKSIZE and DSORG.
The DCB information can be supplied in the DD statement. The sysem looks for DCB information in the program code first.
Q: How do you designate a comment in JCL?
A: The comment statement is //* followed by the comments.
Q: What is the meaning of the EXEC statement keyword, COND? What is its syntax?
A: COND specifies the conditions for executing the subsequent job step. The value after the COND= is compared to the return codes of the preceding steps and if the comparison is true, the step is bypassed.
Q: What is the improvement to COND= in the latest version of MVS?
A: MVS now allows for an IF bracketed by an END IF around any job step to replace the COND= syntax. Again, if the IF statement is true, the step is bypassed.
Q: What is the purpose of the PARM keyword in the EXEC statement?
A: The value after the PARM= specifies control information to be passed to the executing program of the job step.
Q: What is the purpose and meaning of the REGION keyword and what JCL statement is it associated with?
A: REGION specifies the maximum CPU memory allocated for a particular job or job step. If REGION is in the JOB card, it relates to the entire job; if in the EXEC statement, it relates to the job step.
Q: What is the purpose and meaning of the TIME keyword and what JCL statement is it associated with?
A: TIME specifies the maximum CPU time allocated for a particular job or job step. If TIME is in the JOB card, it relates to the entire job; if in the EXEC statement, it relates to the job step.
Q: What is the meaning of data definition name (ddname) and dataset name (dsname) in the DD statement?
A: Data definition name is the eight character designation after the // of the DD statement. It matches the internal name specified in the steps executing program. In COBOL that's the name specified after the ASSIGN in the SELECT ASSIGN statement. Dataset name is the operating system (MVS) name for the file.
Q: How is the keyword DUMMY used in JCL?
A: For an output file DUMMY specifies that the output is to be discarded. For input it specifies that the file is empty.
Q: What does the keyword DCB mean and what are some of the keywords associated with it?
A: DCB stands for data control block; it is a keyword for the DD statement used to describe datasets. Keywords associated with it are BLKSIZE, DEN, LRECL and RECFM.
Q: What is the difference between BLKSIZE and LRECL?
A: BLKSIZE specifies the number of bytes.
1.8. JCL UTILITIES
Some common utilities used:
· Copy one sequential file to another
· Create datasets with input dataset as DUMMY
· Copy the partitioned datasets
· Compress the partitioned datasets
· Include members of PDS within a copy transaction
· Exclude members of PDS with in a copy transaction
· Catalog datasets
· Un-catalog datasets
· Rename the datasets
· Create the index for a generation data groups
· Delete the Index for a generation data groups
· Compare two partitioned datasets
· Compare two sequential datasets
· Create a empty dataset
· Create generation data groups
1.9. ABEND CODES
Caused by the subscript being out of range
Caused by invalid address specification. i.e. The address points to an instruction, control word or data outside the available real storage
Caused by a bad data. i.e. Data exception. When we are moving an alphanumeric field to a numeric computational field this Abend occurs. The result is an Abend failure
Caused by a job being cancelled by the operator, due to a request by the program for an unavailable resource.
Caused by end of volume being encountered.
Caused when CPU time assigned to the job, job step, or procedure has been exceeded. i.e. Time out error.
This abend occurs if the DD statement referenced by UNIT=AFF statement is not closed before the DD statement that comes before it.
Caused when a wait state exceeds an installation-defined time limit.
Caused by lack of sufficient Secondary space
Caused by lack of sufficient Primary space
Caused by lack of space for PDS (Partitioned data set)