Under certain situations IMS™ applications cannot complete. When such a condition occurs, IMS abnormally ends the MPR with a status code (such as U0777) and reschedules it. This action is not apparent to the conventional 3270-type user.

However, when an IMS TCP/IP transaction is abnormally ended, the action is apparent to the client because the connection between client and server is lost when the server MPR is abnormally ended. In this case, IMS TM reschedules the transaction and places the input message (including the TIM) back on the message queue. When the transaction is rescheduled and issues a GU for the TIM, the socket described in the TIM no longer represents a valid connection. and the associated TAKESOCKET call fails. At this time, the Assist module detects the failure of the socket call and returns a ZZ status code to the server program. Upon receipt of this status code, the server program should end normally.