Interface VTAM Session

In cases where a WST/DTF VTAM® session is active, but becomes inactive, the CICS® Interface quiesces the node. Pending requests are allowed to complete, even though they can fail. The number of WSTs for the node is reduced to one.

At this point, if the WST is in session with a local DTF, and ESF mode is allowed, the WST switches to ESF mode. An ESF MODE message is displayed to IUI users, stating that a IBM® Connect:Direct® session error occurred, but ESF MODE is available. Under ESF operation, only the SUBMIT options are displayed on the PRIMARY MENU.

ESF mode operation is enabled for the entire interface through a CONFIGURATION control parameter; ESF mode operation is enabled for each user through a user profile parameter. When a WST fails to establish or drops a DTF session, and ESF is not allowed, then the WST remains attached, but all user requests for the node are rejected.

The WST periodically tries to establish or re-establish (retry) a session with the associated DTF. The CONFIGURATION control parameter session retry interval defines the time lapsed between retries for session connection. An additional CONFIGURATION control parameter, the ESF session retry interval, defines the time elapsed between retries of a dummy DTF session to check if ESF mode has returned to primary mode.