Changing the default maximum number of active parallel subtasks

During processing in PARALLEL mode, DFSMSdss limits the number of active subtasks to avoid exhausting virtual storage in the DFSMSdss address space. When the number of active parallel subtasks reaches the DFSMSdss determined value, DFSMSdss waits for any executing subtasks to complete before scheduling a new subtask.

This function is affected by setting the one byte field at offset X'4C' in ADRPATCH. The settings are listed below:

X'00': DFSMSdss functions normally as described above. The maximum number of active parallel substasks is determined by DFSMSdss.
Any setting from X'01' to X'FF': Specifies the maximum number of active subtasks that DFSMSdss should allow to execute in parallel.

To override the default dynamically, you can use the SET PATCH command to set the patch byte at offset X'4C' to any value from X'01' through X'FF'. To override the default permanently (for example, to allow a maximum of X'32' active parallel subtasks), modify the sample JCL (see Sample JCL) as follows:

//SYSIN DD *
  NAME ADRDSSU ADRPATCH
  VER   4C        00
  REP   4C        32