Initializing the USERVAR to manage terminal sessions for XRF

VTAM® uses a variable called USERVAR to associate a user's logon message with the application name of the currently active IMS subsystem.

The two subsystems in an Extended Recovery Facility (XRF) complex have different application names.

During IMS initialization (and later, during XRF takeover), to allow terminals to log on to the correct subsystem, IMS or network operators must initialize the VTAM USERVAR tables.

If you are not using the VTAM USERVAR Management Enhancement in your network, the network operator must enter the MODIFYprocname, USERVAR command for the alternate subsystem VTAM if it owns terminals. You might also have to tell operators for other VTAMs that communicate with the XRF complex to enter the z/OS® MODIFY command to change the application name in their USERVAR tables.

The active IMS subsystem issues a MODIFY command to tell its own VTAM to initialize the application name in its USERVAR table.

If you are using the VTAM USERVAR Management Enhancement in your network, the network operator should not initialize the VTAM USERVAR table nor use a Tivoli® NetView for z/OS program (CLIST) to propagate the table to other VTAM nodes. It is also not necessary for the operator to enter the z/OS MODIFYprocname, USERVAR command to change the application name in the USERVAR tables. The VTAM USERVAR Management Enhancement does all of this for IMS.