CLASS Parameter

CLASS Parameter

Note! CLASS parameter can be coded only at the job level.

What is CLASS Parameter?

  • The CLASS parameter is used to classify the jobs. The classification is based on how much time they are running. i.e., SHORT RUN or LONG RUN jobs.
  • The CLASS parameter is a keyword parameter and is optional.
  • CLASS parameter values are predefined in the project during installation.
  • The CLASS parameter is used to achieve a good load balance in the system.

Syntax -

CLASS=class-character
class-character Represents a single character value. CLASS parameter value allows alphabets (A to Z), and numbers (0 to 9).
In total, 36 different values are allowed as CLASS parameter values.

Default and overrides -

The system uses an installation-defined default if the CLASS parameter is not coded.

Examples -

CLASS parameter values definition (Assumption) -

CLASS parameter value Description Duration
A Shortest running jobs 10 Seconds
B Shortest running jobs 30 Seconds
..... ..... .....
Z Medium time running jobs 2 hours
..... ..... .....
8 Longest running jobs More than 24 hours
9 System default if not coded Any time

Scenario - Assume that the below jobs are using same files for processing.

JOB1 -

//MTHUSERC JOB (MTH1234),'PAWAN Y',CLASS=B,NOTIFY=&SYSUID

JOB2 -

//MTHUSERC JOB (MTH1234),'PAWAN Y',CLASS=Z,NOTIFY=&SYSUID

What will happen if both jobs are submitted at the same time?

JOB1 starts executing first, and JOB2 will be on hold. Once JOB1 execution is completed, JOB2 starts execution.

More info -

Why CLASS Parameter?

Let us assume two jobs are submitted at the same time, and those are using the same set of files. Among those two jobs, one job completes in 1 min, and the other takes 10 mins. If there is no classification, it is ambiguous to predict the results. Both jobs may be in the hold (contention) for the same resources.

CLASS parameters avoid contention by running the shortest job first by assigning a priority CLASS value and long-running job triggers next. So there will be no contention.

How can we get the CLASS parameter details?

The CLASS parameter definition can change from project to project. In some projects, CLASS=A may assign to short-term jobs. Other projects may assign CLASS=A to long-term jobs. It is always advisable to check with your team lead, system operations, and production support teams to get the CLASS parameter (This applies only to the PRODUCTION jobs).

Coming to the test environment, you can get this information from your team.