Enabling MSC with the MSC= execution parameter

You enable the Multiple Systems Coupling (MSC) feature in an IMS system by specifying MSC=Y in the DFSPBxxx member of the IMS PROCLIB data set.

If you are enabling dynamic definition for MSC resources, the IMS system must configured to support dynamic definitions, with features such as the CSL Operations Manager (OM) and the Structured Call Interface (SCI) enabled. You also need a type-2 command interface such as the TSO SPOC. If you are using the IMSRSC repository, the Resource Manager (RM), the Repository Server, and the Common Queue Server must also be enabled.
When MSC is enabled in an IMS system by coding the MSC=Y execution parameter, MSC resources do not need to be defined by using stage-1 system definition macros before IMS is started. If MSC resources are defined during IMS system definition, the MSC resources are loaded during IMS startup.
Recommendation: To ease operations when dynamic MSC is enabled and MSC resources are no longer defined using the system definition process, specify the MSC=Y execution parameter, even if MSC resources are defined with the system definition process.
You might enable MSC without defining any MSC resources during system definition in the following cases:
  • The MSC resources are already defined in the IMSRSC repository
  • You plan to create MSC resources by using IMS type-2 CREATE commands. In this case, the dynamic definition of MSC resources must be enabled.
  • The IMS system is a back-end IMS system in a shared-queues group that does not require any MSC links. MSC is being enabled only to process messages on the shared queue that were previously transmitted on an MSC link.

To enable MSC:

Procedure

  1. Define one or more local system IDs (SYSIDs) for the IMS system by using the SYSID parameter in the MSC section of the DFSDFxxx member of the IMS PROCLIB data set.
    If one or more MSNAME macros are included in the IMS system definition, coding the SYSID parameter is optional.
  2. Optional: Optionally, enable dynamic definition of MSC resources by specifying MSCRSCS=DYN in the MSC section of the DFSDFxxx member.
    Dynamic definition of MSC resources must be enabled to create or delete MSC resources by using IMS type-2 commands.
  3. If MSCRSCS=DYN, specify your options for importing your MSC resource definitions on the AUTOIMPORT parameter in the DYNAMIC_RESOURCES section of the DFSDFxxx member.
    • To have IMS automatically detect and load your MSC resource definitions during startup, regardless of how they were defined and where they are stored, specify AUTOIMPORT=AUTO. AUTOIMPORT=AUTO is the default.
    • To have IMS load MSC resources from only the IMSRSC repository, specify AUTOIMPORT=REPO. When AUTOIMPORT=REPO, IMS imports both MSC and MODBLKS resources from the IMSRSC repository.
    • To have IMS load only MSC resources that are defined during IMS system definition, specify AUTOIMPORT=MSCGEN.
    • To prevent loading any MSC resources during startup, specify AUTOIMPORT=NO. The MSC resource definitions will need to be either imported later from the IMSRSC repository by using the IMPORT DEFN command or defined by using IMS type-2 CREATE commands.
  4. Enable MSC by specifying the MSC=Y execution parameter in your startup procedure.
  5. Cold start IMS.
    If any MSC resources were generated into the DFSCLL3x member of the IMS.SDFSRESL data set during system definition, IMS loads them into the online system during startup.