Writing your own listener

The IP CICS® socket interface provides a structure that supports multiple listeners. These listeners can be multiple copies of the IBM-supplied listener, user-written listeners, or a combination of the two. You can also run without a listener.

For each listener (IBM-supplied or user-written), there are certain basic requirements that enable the interface to manage the listeners correctly, particularly during initialization and termination. They are:

Each listener instance must have a unique transaction name, even if you are running multiple copies of the same listener.
Each listener should have an entry in the CICS sockets configuration data set. Even if you do not use automatic initiation for your listener, the lack of an entry would prevent correct termination processing and could prevent CICS from completing a normal shutdown.

For information on the IBM-supplied listener, see CICS application transaction (IBM listener).