There are two scenarios for shutdown, normal and immediate.
The normal shutdown scenario is the recommended method for stopping the CICS® Transaction Gateway. The immediate shutdown scenario is not recommended except in emergencies; there is no guarantee that work in progress will complete.
XA transactions that are in post-prepare state are not rolled back during an immediate shutdown. If no other instance of the CICS Transaction Gateway is running under the same RRM name, it is not possible for the transaction manager (WebSphere®) to recover indoubt XA transactions until the CICS Transaction Gateway is restarted.
If TCP/IP load balancing is in use, multiple CICS Transaction Gateways are running under the same RRS name. Requests to resolve indoubt XA transactions are sent to other Gateway daemons that are still running in the same Gateway group.
You can perform an immediate shutdown if a normal shutdown is taking too long. You cannot request a normal shutdown after you have issued the command for an immediate shutdown.