CICS socket interface and listener application data

The IP CICS® socket interface and listener support automatic registration of application data to be associated with the TCP connection. Automatic registration occurs when the following socket commands are run and the underlying MVS™ subtask is not detached:

After CONNECT, connect()
Before GIVESOCKET, givesocket()
This function is automatic only for the IBM® listener. User-written listeners can issue the SIOCSAPPLDATA IOCTL command with their own application data.
Before LISTEN, listen()
After TAKESOCKET, takesocket()

The IP CICS socket interface resource manager task-related user exit (TRUE) processes automatic registration when the resource manager makes an additional SIOCSAPPLDATA IOCTL call. This additional call is made only when the APPLDAT or LAPPLD configuration options are specified as YES. The APPLDAT configuration option is global; all socket-enabled transactions are enabled to automatically register application data against their socket endpoints for the socket commands in the previous list. Regardless of how the APPLDAT on the listener is configured, listeners can optionally be enabled or disabled. The IBM listener also automatically registers application data for accepted connections to be given when the application data being registered contains data about the child process expected to take the given socket. The listener's security exit can also enable or prohibit this action.

Although the application data configuration options can be specified with the EZACICD macro and the EZAC configuration transaction, use the EZAO operator transaction to dynamically alter the same options temporarily. In addition, use the EZAO operator transaction to show the current state of application data registration.