Resolving indoubt UOWs when using group attach

If you are using group attach and the connection between CICS® and DB2® is broken, CICS might not reconnect to the same DB2 subsystem—it might choose a different member of the data-sharing group of DB2 subsystems. This means that if indoubt UOWs are being held by the first DB2 subsystem to which CICS connected, they cannot be resolved.

To solve this problem, CICS maintains a history of the last DB2 data-sharing group member to which it connected, which is cataloged and maintained across warm, emergency and cold starts (but not initial starts). During connection or reconnection to DB2, the CICS DB2 attachment facility checks this history to see if any outstanding UOW information is being held for the last DB2 data-sharing group member to which it connected, and acts as follows:
  • If no outstanding UOW information is being held and if CICS has not performed an emergency restart, group attach operates normally and chooses any active member of the data-sharing group for the connection. If CICS has performed an emergency restart, CICS attempts to connect to the member that it was last connected to.
  • If outstanding UOW information is being held, the next action depends on the setting you have chosen for the RESYNCMEMBER attribute of the DB2CONN definition.
    • If RESYNCMEMBER is set to YES, indicating that you require resynchronization with the last recorded DB2 data-sharing group member, CICS ignores the group attach facility, and the CICS DB2 attachment facility waits until it can reconnect to that last connected DB2 data sharing group member, to resolve the indoubt units of work. UOWs which are shunted indoubt are not included in this process, because CICS itself is unable to resolve those UOWs at this time. Resynchronization for those UOWs will occur when CICS has resynchronized with its remote coordinator.
    • If RESYNCMEMBER is set to NO, perhaps because you want to reconnect as fast as possible, CICS makes one attempt to reconnect to the last recorded DB2 data-sharing group member. If this attempt is successful, the indoubt UOWs (with the exception of UOWs that are shunted indoubt) can be resolved. If it is unsuccessful, CICS uses group attach to connect to any active member of the DB2 data-sharing group, and the warning message DFHDB2064 is issued stating that there may be unresolved indoubt UOWs with the last recorded member.

See DB2CONN resources for information on setting RESYNCMEMBER. The RESYNCMEMBER option can also be set using a SET DB2CONN RESYNCMEMBER command.