Use alternate response PCBs in IMS transactions

When an IMS transaction uses alternate response PCBs (ISRTs to the ALTPCB, or issues a CHNG call to a modifiable PCB), the pre-routing exit (DFSYPRX0) is invoked to determine if the message should be rerouted.

If the message is to be rerouted, the destination resolution exit (DFSYDRU0) is invoked to confirm the destination and prepare the header information See Use OTMA exits in IMS and The pre-routing exit DFSYPRX0 for information about these exit programs.

Unless action is taken in the exits, all output from IMS transactions initiated from an IBM MQ queue manager, whether to the IOPCB or to an ALTPCB, will be returned to the same queue manager.