Top 25 JCL Interview Questions

1) Explain what is JCL?

JCL stands for Job Control Language.  It is the command language of Multiple Virtual Storage (MVS). It is the normally used in Operating System in the IBM Mainframe computers.

2) Explain what is the use of JCL?

  • It is used for the deleting creating, the Data Sets, GDG’S and VSAM clusters.
  • It is used for comparing the files and PDS members
  • It is used for compiling and executing the programs which includes batch programs as well
  • It is used for merging and sorting on file data

3) Mention the types of job control statements?

The types of job control statements are

  • JOB – to identify the Job
  • DD  –  to supply the I/O files needed for the execution of the program
  • EXEC – to identify which program has to be executed

4) Explain how JCL works?

JCL recognizes the program to be executed, the inputs that are required and location of the input/output and informs the Operating System through Job control Statements.

5) Mention what is the JCL statement consists of?

JCL statement consists of

  • Name field (optional)
  • Operation field
  • Operand
  • Comments

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6) What is the syntax of JCL statement?

The syntax of JCL statement is,

//Job-name JOB Positional-param, Keyword-param

7) Explain what is DD statement is used in JCL?

DD statement is used in JCL is used to identify the source of input and the placement of output information.


8) Explain what EXEC statement is and what is the syntax of EXEC statement used in JCL?

EXEC statement holds the job step program or procedure information.  The syntax of EXEC statement used in JCL is

//Step-name EXEC Positional-param, Keyword-param

9) Explain what are JCLLIB and STEPLIB in JCL?

Both libraries specifies the private libraries that should be searched before the default system libraries does in order to locate a program to be executed.

  • JCLLIB identifies the libraries that the system will search for include groups or procedures named in EXEC statements
  • JOBLIB applies to all steps in the job while STEPLIB applies only to the particular step.

10) Explain what is DSN parameter and DISP parameter is used for?

  • DISP parameter: It is used to specify the disposition of dataset which is coded on DSN parameter
  • DSN parameter: It is used to specify the data set name

11) Explain what JCL Procedures?


The JCL Procedures are nothing but a set of statements inside a JCL, grouped together to perform a particular function. Procedure can be used to achieve parallel execution of a program using multiple input files.

12) What is Cataloged Procedures?

From the JCL, when the procedure is separated out and coded in a different data store, then it is referred as a Cataloged Procedure.

13) Mention what happens when COND is coded in JOB statement and when COND is coded inside EXEC statement?

  • When COND is coded in JOB statement, the condition is tested for every job step. When the condition is true for any particular job step, it is byepassed along with the job steps.
  • When COND is coded inside EXEC statement of a job step, and the condition is true, then only that particular job step is bypassed, and execution will be carried out from the next job step

14) Mention what is DSN in JCL and what are the parameters to declare the DSN?

In JCL, a dataset name determines the name of a file and it is referred by “DSN”.

The DSN value can comprise of sub-names each of 1 to 8 characters length, separated by periods and of total length of 44 characters (alphanumeric).

15) Explain how would you create a temporary dataset? And where will you use them?

Temporary dataset can by created either by specifying the temporary file indicator as in SDN=&&Temp or by not specifying any DSName.

16) Explain what is SOC4 error?

SOC4 error is for storage violation error and can be due to many reasons. For example, invalid address due to script error.

17) Explain in ways data can be passed to a COBOL program from JCL?

A data can be passed to a COBOL program from JCL through

  • Files
  • SYSIN DD statement
  • PARM parameter

18) Explain how can you access an uncataloged dataset in a JCL?

You can access an uncataloged dataset in a JCL by using the VOL and UNIT serial parameters in the dataset DD statement.

19) Explain what is “Cond= even” and “Cond=only”?

  • Cond=even indicates to execute this step EVEN if any previous step is terminated abnormally.
  • Cond=only indicates to execute this ONLY if any previous step is terminated abnormally

20) Explain what is the use of IEBGENER utility?

The use of IEBGENER utility is used for copying the data from

  • one PS to another PS
  • OR Member of a PDS  to another PS
  • OR PS to member of PDS.

21) Is it possible to code instream data in a PROC?

No, it is not possible to code instream data in a PROC.

22) Explain in DD statement what is the use of DCB parameter?

In DD statement the use of DCB parameter is to give the detail information of the physical characteristics of a dataset.

23) Explain how can you direct the data to spool using SYSOUT option?

You can direct the data to spool using SYSOUT option “SYSOUT=*”

24) Explain what is the difference between JES3 and JES2?

The difference between JES3 and JES2 is that,

  • JES3 assigns datasets for all the steps before the job is scheduled.
  • JES2 assigns datasets required by a step just before the step executes.

25) Mention what is the difference between specifying DISP=OLD and DISP=SHR for a dataset?

The difference between specifying DISP=OLD and DISP=SHR for a dataset is that,

  • DISP=OLD: It reads data from beginning of dataset. But incase if you try to modify or write, then it will overwrite on existing data. i.e old data is lost
  • DISP=SHR: Its read-only file. In this, multiple user can share the data

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