Termination of Persistent Session Tracking

If a session terminates before IMS has closed the VTAM® access control block (ACB), VTAM persistent session tracking, and the ability of IMS to reconnect, are terminated on all terminals.

An IMS-initiated shutdown could be executed, for example, by issuing the /CHECKPOINT FREEZE or /STOP DC or /CLSDST commands.

A VTAM session is also disconnected if VTAM persistent session tracking is prematurely terminated due to a non-IMS-initiated session close if that session close occurred before an IMS restart completion, which can happen for one of the following reasons:
  • Remote operator-initiated session termination; executing, for example, the /RCL command
  • Network operator-initiated session termination; executing, for example, the VARY NET or INACT commands
  • Timeout of persistent session tracking indicated by the PSTIMER value

If IMS is defined for RNR on MNPS, the VTAM Network Operator can determine whether persistence is currently active by using the VTAM DISPLAY ID command.

When shutting down VTAM, the HALT NET or HALT NET, QUICK commands terminate session persistence, and the HALT NET, CANCEL command maintains session persistence.