The configuration of your Gateway daemon directly influences the choices available for Gateway identity the rules are detailed in this section.
CICSTG.<APPLID qualifier>.<APPLID>[.UA]
If
XA transaction support is not enabled, the resource manager name is
appended with ".UA". The fully-qualified APPLID is used to identify the Gateway daemon to CICS® servers connected using the IPIC protocol.
CICSTG.<APPLID>.UA
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.
You can leave the APPLID and qualifier undefined if XA transaction support is disabled (xasupport=off). In this situation the Gateway uses the JOBNAME as the identifier in log messages and SMF records.
The defined APPLID qualifier or APPLID are not explicitly verified for uniqueness during initialization. If they are not unique within the sysplex or your wider organization, failures might occur during initialization or later when connecting to a CICS server.
It is recommended that you choose a naming convention that gives each Gateway daemon an APPLID that is unique within the sysplex or Gateway group and a fully-qualified APPLID that is unique within the wider organization.
When the fully-qualified APPLID is used for RRS registration the Gateway fails to initialize if another address space, usually a Gateway daemon, within the sysplex is already registered using the same resource name.
You might encounter connection problems if more than one Gateway attempts to establish an IPIC connection to a CICS server when both have the same APPLID or fully-qualified APPLID. The Gateway daemons might not be within the same sysplex or might be connecting from a different platform.