The local CICS region name

A CICS® Transaction Server for z/OS® region can be known by more than one name.

  • Application identifier (APPLID)
  • System identifier (SYSID)
  • z/OS Communications Server generic resource name

All CICS regions have an APPLID and a SYSID. A terminal-owning region that is a member of a z/OS Communications Server generic resource group also has a z/OS Communications Server generic resource name. z/OS Communications Server generic resource names are described in Configuring z/OS Communications Server generic resources.

APPLID of the CICS region

The APPLID of a CICS system is the name by which it is known in the intercommunication network; that is, its netname.

  • For MRO, CICS uses the APPLID name to identify itself when it signs on to the CICS interregion SVC, either during startup or in response to a SET IRC OPEN command.
  • For ISC over SNA, the APPLID is used on a z/OS Communications Server APPL statement, to identify CICS to z/OS Communications Server.
  • For IPIC, the APPLID attribute of an IPCONN resource identifies the APPLID of the remote system.

You specify the CICS APPLID on the APPLID system initialization parameter. The default value is DBDCCICS. This value can be overridden during CICS startup.

Within a z/OS sysplex, the APPLID of each CICS region must be unique. If your CICS regions are not part of a sysplex, if your network consists of more than one sysplex, or if your CICS regions communicate with systems outside the local sysplex, it is advisable to keep APPLIDs unique across the network if possible. If your network does contain systems with identical APPLIDs, on IPIC connections you can specify the NETWORKID option; this unique value enables you to connect to two or more remote regions that have identical APPLIDs.

SYSID of the CICS region

The SYSID of a CICS region is a name (1–4 characters) known only to the CICS region itself. It is obtained (in order of priority) from:

  1. The startup override
  2. The SYSIDNT operand of the DFHSIT macro
  3. The default value CICS.

The SYSID of your CICS region might also have to be specified in the DFHTCT TYPE=INITIAL macro if you are using macro-level resource definition. The only purpose of the SYSIDNT operand of DFHTCT TYPE=INITIAL is to control the assembly of local and remote terminal definitions in the terminal control table. The SYSID of a running CICS region is always the one specified by the system initialization parameters.