Classifying Jobs

WLM classification is responsible for assigning a service class and optionally a report class to a job based on the classification rules in the WLM policy. A service class is a group of work which has the same performance goals, resource requirements, or business importance. For workload management, you assign a service goal and optionally a resource group to a service class. WLM starts initiators on a service class basis.

A report class is a group of work for which reporting information is collected separately. For example, you can have a report class for information combining two different service classes, or a report class for information on a single transaction. A report class is not used by WLM initiator management.

Before OS/390® JES3 Version 2 Release 8, jobs were classified during execution. With OS/390 JES3 Version 2 Release 8, jobs are classified at the end of C/I processing after user exit IATUX09 has been called. Classification is performed for all batch jobs, not just for jobs in WLM-managed groups.

When a job is classified, the following information is provided to you so that you can classify jobs:
  • Job name (called transaction name in the classification rules)
  • Job class (called transaction class in the classification rules)
  • PERFORM parameter from the JOB statement. (The PERFORM parameter on the EXEC statement is not used and cannot be used to assign a new service class when a new step begins to execute.)
  • Owner (RACF® user id)
  • Priority
  • Accounting information
  • Subsystem type - JES
  • Subsystem name - JES3 subsystem name (typically "JES3")
See z/OS MVS Planning: Workload Management for more information on how to setup classification rules and service classes.
After a job is classified, it may be reclassified:
  • When a job's priority is changed as a result of a *MODIFY,J=job,P=xx command or because of deadline scheduling. Because a job's priority is one of the inputs to classification, the job's service class may change when the priority is changed.
  • When a job's class is changed with a *MODIFY,J=job,CLASS=class command. Because a job's class is one of the inputs to classification, the job's service class may change when the class is changed.
  • When a new WLM service definition is installed and activated. The classification rules can be changed and service classes can be added or deleted only by installing and activating a new WLM service definition. When this occurs, jobs are reclassified to pick up the latest changes to the WLM service definition.

A job is not reclassified when its priority is changed through the use of the SAGER or MAGER parameters on the SELECT initialization statement. Unlike deadline scheduling, priority aging only updates a job's priority temporarily for the purposes of moving the job up in the queue ahead of other jobs. When a job has completed setup or has been selected to run, the priority is restored to its original value.