JCL Interview Questions and Answers

9/17/2009 No Comment

IBM JCL Mainframe Interview Questions and Solutions.

IBM Mainframe JCL Codes Questions.

What is primary allocation for a Data Set?
Answer : The space allocated when the Data Set is first created .

What is the difference between primary and secondary allocations for a Data Set?
Answer : Secondary allocation is done when more space is required than what has already been allocated

How many extents are possible for a Sequential File ? For a VSAM File ?
Answer : 16 extents on a volume for a Sequential File and 123 for a VSAM File

What does a disposition of (NEW,CATLG,DELETE) mean?
Answer : That this is a new Data Set and needs to be allocated, to CATLG the Data Set if the step is successful and to delete the Data Set if the step abends.

What does a disposition of (NEW,CATLG,KEEP) mean?

Answer : That this is a new Data Set and needs to be allocated, to CATLG the Data Set if the step is successful and to KEEP but not CATLG the Data Set if the step abends Thus if the step abends, the Data Set would not be catalogued and we would need to supply the Vol ser the next time we refer to it

How do you access a File that had a disposition of KEEP?

Answer : Need to supply volume serial no VOL=SER=xxxx MOD,DELETE

What does a disposition of (,DELETE) mean ?

Answer : The MOD will cause the Data Set to be created (if it does not exist), and then the two DELETE will cause the Data Set to be deleted whether the step abends or not This disposition is used to clear out a Data Set at the beginning of a job

What is the DD statement for a output File?

Answer : Unless allocated earlier, will have the following parameters: DISP=(NEW,CATLG,DELETE), UNIT , SPACE & DCB

What do you do if you do not want to keep all the space allocated to a Data Set?

Answer : Specify the parameter RLSE ( release ) in the SPACE. Eg: SPACE=(CYL,(50,50),RLSE)


Answer : This is a new File and create it, if the step terminates normally, pass it to the subsequent steps and if step abends, delete it This Data Set will not exist beyond the JCL

How do you create a temporary Data Set? Where will you use them?

Answer : Temporary Data Sets can be created either by not specifying any DSNAME or by specifying the temporary File indicator as in DSN=&&TEMP We use them to carry the output of one step to another step in the same job The Data Set will not be retained once the job completes

How do you restart a proc from a particular step?

Answer : In job card, specify RESTART=proc step step name where procstep = name of the jcl step that invoked the proc and stepname = name of the proc step where you want execution to start

How do you skip a particular step in a proc/JOB?

Answer : Can use either condition codes or use the jcl control statement IF (only in ESA JCL)

A PROC has five steps Step 3 has a condition code How can you override/nullify this condition code?
Answer : Provide the override on the EXEC stmt in the JCL as follows: //STEP001 EXEC procname,CONDstepname=value All parameters on an EXEC stmt in the proc such as COND, PARM have to be overridden like this

How do you override a specific DDNAME/SYSIN in PROC from a JCL?

Answer : // DSN=

What is NOTCAT 2?

Answer : This is an MVS message indicating that a duplicate catalog entry exists Eg, if you already have a Data Set with dsn = 'xxxxyyyy' and u try to create one with disp new,catlg, you would get this error the program open and write would go through and at the end of the step the system would try to put it in the system catalog at this point since an entry already exists the catlg would fail and give this message you can fix the problem by deleting/uncataloging the first data set and going to the volume where the new Data Set exists(this info is in the msglog of the job) and cataloging it

What is 'S0C7' abend?

Answer : Caused by invalid data in a numeric field

What is a S0C4 error ?
Answer : Storage violation error - can be due to various reasons eg: READING a File that is not open, invalid address referenced due to subscript error

What are SD37, SB37, SE37 abends?

Answer : All indicate Data Set out of space. SD37 - no secondary allocation was specified. SB37 - end of vol and no further volumes specified. SE37 - Max of 16 extents already allocated
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