About SSTM

The Subsystem Started Task Manager (SSTM) provides full JCL functionality within the CICS and IMS subsystems. This JCL functionality is equivalent to that of a task started under z/OS.

A CICS (MSS) Region typically uses more than one SEP to process online transactions. In the CICS region, each SEP runs the same JCL using the same job name and number. Within the region, all CICS SEPs JCL job activities and their outputs can be found under this one job number. All of the CICS SEPs:
  • Share permanent datasets whether these are allocated via the JCL or via SVC99. The system does not provide any access serialization capabilities. Any non-read access to shared datasets must be serialized, if necessary, by the user.
  • Do not share in-stream (DD * and DD DATA) datasets.
  • Do not share other datasets (temporary and SYSOUT datasets).
  • Contain in the joblog dataset, JCL logged activity incurred by all CICS SEPs with identification of the originating SEPs process id.
    Important: You must serialize CICS access to each DDname that refers to the INTRDR writer. To achieve this, issue a CICS ENQ command for the DDname before opening the file, and a corresponding DEQ command after closing the file.
An IMS subsystem uses one SEP for each Message Processing Region (MPR) and will typically have more than one MPR. Each MPR has a unique job number, but will very likely have the same job name. Each MPR’s activity and outputs are independent as with batch jobs, and can be found under the MPR’s job number.

When SSTM is enabled, you can specify an application parameter (APARM) in the JCL for an IMS MPR. The APARM is available to the AIBTDLI INQY ENVIRON call from IMS applications and data capture exit routines. The value of the APARM is taken from the JCL when the first message is processed in the MPR. All MPRs share the same JCL file.