z/OS JES3 Initialization and Tuning Reference
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Statement Summary

z/OS JES3 Initialization and Tuning Reference
SA32-1005-00

Table 1. CLASS Summary
Variable Value
Required/Optional Statement Optional
Statement Default None
Placement in Initialization Stream This statement must follow the ENDJSAM statement.
Coding Considerations
  1. You can define up to 255 classes.
  2. This statement has dependencies on the SPART initialization statement. During a hot start with refresh, JES3 does not process the SPART statement but uses the SPART statement from the last warm or cold start. If you add a SPART statement during a hot start with refresh, JES3 ignores it and issues error messages if the CLASS statement you use references the SPART statement that you attempted to add during a hot start with refresh.
  3. The IORATE= and LSTRR= keyword parameters are ignored for job classes that are associated with WLM-managed job class groups.
  4. For started tasks, all CLASS initialization parameters are ignored except the following:
    • CI scheduling (CIDEMAND parameter on the CLASS initialization statement)
    • Job class group name (GROUP parameter on the CLASS initialization statement)
    • Device fencing (EXRESC and DEVPOOL parameters on the GROUP initialization statement associated with this CLASS initialization statement)
    • Spoolpartitioning (SPART parameter on the CLASS initialization statement)
    • Track group allocation (TRKGRPS parameter on the CLASS initialization statement)
Security Usage None
Performance Considerations None
Initialization Stream Overrides
  1. The specification of the TRKGRPS parameter on the SYSOUT statement and //*MAIN statement overrides the specification on the CLASS statement. If you do not specify the TRKGRPS parameter on the CLASS statement or any of the statements that override the CLASS statement, JES3 uses the specification given (or defaulted to) on the MAINPROC statement.
  2. For individual jobs, the //*MAIN JES3 control statement and the EXEC JCL statement can override certain parameters on the CLASS statement. See individual parameter descriptions.
Restart or Command Modification
  • Cold start, warm start, or hot start with refresh for all parameters. If you delete a CLASS initialization statement during a hot start with refresh and there are jobs referencing that job class, the job's will be placed in hold status. JES3 failures can occur if any of these jobs are in execution.
  • Use the *MODIFY,G,main,CLASS command to activate or deactivate a class.
  • Use the *MODIFY,C=class,SP=spart command to modify the spool partition.
  • Use the *MODIFY,C=class,SDEPTH= command to modify the setup depth (SDEPTH).
  • Use the *MODIFY,C=class,TDEPTH= command to modify the TDEPTH parameter.
  • Use the *MODIFY,C=class,MDEPTH= command to modify the MDEPTH parameter.
  • Use the *MODIFY,C=class,TLIMIT= command to modify the TLIMIT parameter.
  • Use the *MODIFY,C=class,GROUP= command to modify the group assigned to a class.
  • Use the *MODIFY,C=class,JESMSG= command to modify whether to create or suppress the JESMSGLG data set for jobs that run in this class.
  • Use the *MODIFY,C=class,SPIN= command to modify whether to spin off or not spin off the JESlog (JESMSGLG and JESYSMSG) data sets for jobs running in this class and whether the spin off is automatic.
  • Use the *MODIFY,C=class,SYSSYM= command to modify the SYSSYM parameter.
Parent topic: CLASS (JES3 Job Class Definition)

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