What is the CLASS Parameter?
JCL CLASS Parameter is a Keyword Parameter and CLASS Parameter defines an input CLASS in of a schedule JOB. It is used to tell the operating system about the nature of the job which we are submitting.
So, we can use a CLASS Parameter to group similar jobs together according to the time requirements and tape or printer resource needs and that has to be confirmed by your system admin group or scheduling group.
The Syntax of CLASS Parameter:
The JOB-CLASS can take either of these values listed below-
- Any character from A to Z
- Any number from 0 to 9
Here, you see that the CLASS is A and Since this is a key Parameter So you can define CLASS=A after MSGCLASS or after MSGLEVEL as well because it does not follow a particular position.
What can be a practical issue with wrong CLASS?
Sometimes, what happens is that too many jobs run on a particular CLASS and all these Jobs try to refer a particular resource
at the same time and this causes the resource to lock and that is called as Contention.
So, in order to avoid the Contention between multiple jobs, You can schedule different jobs in different Classes so that the same resource should not be used by so many jobs.
Now, how do you decide which job CLASS you have to use?
So, in order to decide which JOB CLASS you need to code in your JCL, you have to check with the job scheduling group or system admin or data center or whatever you call in your particular group, or in your particular project and you have to ask which particular CLASS you need to code in your JCL.
So each job CLASS has its own input Queue and based on what your system admin requires, please code that particular JOB CLASS.