Dynamic MSC using DELTA PLUS

In a static Multiple Systems Coupling (MSC) environment, MSC definitions are defined by the IBM IMS stage-1 macros (MSPLINK, MSLINK, MSNAME, NAME) and by running an IBM IMS sysgen. The MSC control blocks generated by running the IMS sysgen reside in module DFSCLL3x in the IMS.RESLIB.
To add, change, or remove static MSC resources, you must change the macro definitions to include ADD, CHANGE or DELETE and perform an IMS sysgen. You must perform an IMS cold start to bring in the new MSC system definitions. 

In a dynamic MSC environment, the following conditions apply:

• Dynamic MSC processing coexists with the MSC definitions defined in IMS stage-1 sysgen. 
  You define MSC definitions using one of the following methods:
  • In the IMS stage-1 sysgen
  • By using the IMS type-2 commands (CREATE, UPDATE, or DELETE)
  • DELTA  List processing

• Each time an MSC resource is created, modified, or deleted dynamically, IMS logs the event in a X'22' or X'02' log record. During a warm or emergency restart, IMS restores the MSC resources to their state before termination by reading the following log records:
  • X‘4037’ - MSC physical link blocks
  • X’4036’ - MSC logical link blocks
  • X‘4039’ - RCNTs
  • X‘4038’ - MSC PCBs (for bandwidth)
• During ERE processing, additional type ‘22’ log records could be read from the SLDS, after reading the checkpoint records from log records X‘4037’, X‘4036’, X‘4039’. Type ‘22’ log records are generated from IMS type-2 CREATE, UPDATE, or DELETE commands.
• Dynamic MSC updates made by DELTA PLUS are saved in the DELTA PLUS Log or in DELTA PLUS Repository (if repository is enabled, see DELTA PLUS repository).
• Dynamic MSC elements are managed by one of the following methods:
  • Executing IMS type-2 commands CREATE, UPDATE, and DELETE
  • Executing a DELTA List