Avoiding pseudoabend U0830

When an MSC network and an IMSplex with shared queues coexist, errors can occur if you remove IMS systems from, or add them to, the IMSplex or MSC network while messages remain on the shared queues or in flight within the MSC network.

Errors can also occur if the definitions used to route the messages, such as SYSIDs, IMSIDs, or destination names, are changed.

In an IMSplex with MSC, IMS validates SYSIDs, IMSIDs, and destination names when IMS systems retrieve transaction messages from the shared queue for processing. If validation fails, IMS leaves the transaction message on the shared queue and issues a pseudoabend U0830. By taking these precautions you can avoid most U0830 pseudoabends:

  • Prior to migrating or moving IMS systems, dequeue all transaction messages destined for the IMS systems being migrated or moved from the shared queues and the MSC network.
  • Prior to changing any SYSIDs, IMSIDs, or MSNAMEs, dequeue all transaction messages that use these identifiers from the shared queues and the MSC network.
  • After migrating new IMS systems into an IMSplex, wait for all the IMS systems to join the IMSplex and all SYSID tables to be updated before you start dependent regions to process messages
  • When restarting multiple IMS systems with MSC definitions in an IMSplex, if all local SYSIDs in the IMSplex have not been cloned in each IMS system, wait for all of the IMS systems to finish restarting before starting any dependent regions. Until restart is complete, some SYSID tables might not include all of SYSIDs that are not cloned.
  • Verify that MSC is defined to each IMS system in the IMSplex. Messages queued by an IMS that does not have MSC defined will not have the MSC extension prefix and will have zero SYSID values. If this message is processed by another IMS system in the IMSplex that has the MSC feature, a pseudoabend U0830 results with return code 08.

    In an IMSplex, if one IMS system is MSC capable, then all IMS systems in the IMSplex must be MSC capable. To enable an IMS system for MSC, define an MSC link for the IMS system during system definition. This MSC link definition does not need to be functional.

For detailed information about the return codes associated with pseudoabend U0830 and other diagnosis information, see IMS Version 15.5 Messages and Codes, Volume 3: IMSAbend Codes.