Using user variables (USERVAR)

The VTAM® user variable (USERVAR) maps a generic application program name used in a terminal logon to the name of a specific application program, based on the value of the USERVAR. This function is used by IMS™ and CICS® XRF to map user logons to the IMS or CICS application program that is currently active.

You can also use USERVARs in other ways, such as to facilitate migration from one application program release to another. The VTAM user variable:

Enables your installation to use the USERVAR function without having to rely upon NetView® command lists or manual procedures to propagate USERVAR updates. VTAM communicates USERVAR values across domains in the same or different networks.
Enables your application programs to use USERVAR names across VTAM application programming interface (API) in place of logical unit names without requiring code changes.
Enables your terminals to take advantage of USERVAR translation without your having to code interpret tables for them.

The VTAM application programming interface (API) allows application programs to use USERVAR names across the API in place of LU names. Because USERVAR can be used across the API, many application programs that participate in sessions with an XRF-capable application program (such as IMS or CICS) can remain unchanged when USERVARs are used.

Also, because VTAM determines whether a name refers to an LU or to a USERVAR and performs the appropriate translation automatically, you do not have to code an interpret table to specify that a name used in a particular logon is actually a USERVAR.

Note: The generic name used by USERVAR should not be used by ALIAS. An alias CDRSC should not exist in a host where USERVAR mapping is used unless the host is in the same network as the real resources.