TXSeries requires that if an Application ID is specified for a CICS Transaction Gateway client connecting to a TXSeries region, the Application ID must be unique to the TXSeries region.
CICS Transaction Gateway is one of the CICS clients that can be used to connect to a TXSeries region. When you configure the CICS Transaction Gateway to connect to a TXSeries CICS region, the Application ID of the CICS Transaction Gateway client can be specified in the CLIENT SECTION of CICS Transaction Gateway configuration file, ctg.ini.
You can specify an Application ID of length up to eight characters under CICS Transaction Gateway client section. The default value of the field is "*". The value of "*" automatically ensures that the region generates a name for the communication definition that is guaranteed to be unique. If you chose to manually specify an Application ID, you have to ensure that the name is unique across the regions, the CICS Transaction Gateway client is configured to connect.
This configuration is only applicable to TXSeries listeners that are configured on TCP protocol.