CICS Transaction Gateway IPIC connections in CICS are identified by a fully-qualified APPLID.
In remote mode set the fully-qualified APPLID to be used to identify CICS Transaction Gateway to CICS in the configuration file, and in local mode set the fully-qualified APPLID in the application or environment. If the APPLID and APPLID qualifier specified in an IPCONN in CICS® match this APPLID and APPLID qualifier, the configuration of that IPCONN is applied to the connection made by the Gateway daemon.
If there is no matching IPCONN definition, the connection is autoinstalled if the CICS system has been configured to autoinstall IPCONN connections. If you configure CICS not to allow autoinstall of IPCONN connections, only requests that have APPLIDs that are set on the predefined IPCONN definitions are able to connect.
If the configuration file (ctg.ini) contains an APPLID but not an APPLID qualifier, the system uses the default value 9UNKNOWN for APPLID qualifier. For more information, see Gateway APPLID qualifier.
If the Gateway daemon or local mode application is configured with a fully-qualified APPLID, and connects to a CICS server using the IPIC protocol, no other Gateway daemon or local mode application configured with the same fully-qualified APPLID can concurrently establish an IPIC connection with the same CICS server. If the fully-qualified APPLID is not unique, attempts made to connect to a CICS server might be rejected because another connection has already been installed using the same fully-qualified APPLID.
When the Gateway daemon or local mode application is configured with a fully-qualified APPLID, all application requests sent to a CICS server using the IPIC protocol use that fully-qualified APPLID. There is no check of fully-qualified APPLIDs for uniqueness, so you must choose a naming convention carefully to ensure the uniqueness of fully-qualified APPLIDs across the enterprise.
When a Gateway daemon or local mode application without a defined fully-qualified APPLID connects to a CICS server using the IPIC protocol the CICS server generates a fully-qualified APPLID that is unique to that connection. If this Gateway daemon or local mode application connects to multiple CICS servers using the IPIC protocol, each connection's own fully-qualified APPLID is generated independently. Each time that a Gateway daemon or local mode application without a defined fully-qualified APPLID connects to a CICS server using the IPIC protocol, the fully-qualified APPLID that is generated changes and cannot be relied on to be consistent.
If the APPLID and NETWORKID specified in a CICS IPCONN definition match the Gateway daemon or local mode application's APPLID and APPLID qualifier, the configuration of that IPCONN is applied to the connection made by the Gateway daemon. If there is no matching IPCONN definition, the connection is autoinstalled if the CICS system has been configured to allow autoinstall IPCONN connections. If you configure CICS to prohibit the autoinstall of IPCONN connections only requests that have APPLIDs that are set on the predefined IPCONN definitions can connect.
If the APPLID qualifier defined for the Gateway daemon or local mode application is left blank and the NETWORKID in the CICS IPCONN definition is left blank, a match will not occur even if the APPLIDs match, because CICS defaults the blank NETWORKID to the local network ID.