Dynamic USERVAR update session failure

Whenever an abnormal session termination occurs for a session that was initiated using a USERVAR, VTAM® deletes the USERVAR if it is VTAM-managed and dynamic. When the next session request arrives at any host other than the XRF primary host, VTAM repeats the search for the USERVAR and saves the new current value in an automatic USERVAR.

The following kinds of session termination are considered normal because they do not cause the resetting of a dynamic USERVAR:

Requests for conditional or unconditional termination, such as:
- Operator issued the VARY NET,TERM,TYPE=COND|UNCOND command.
- SLU application program issued the TERMSESS OPTCD=COND|UNCOND command.
- Terminal issued (using USS) the LOGOFF TYPE=COND|UNCOND command.
Session setup failures because of the following sense codes:
- 08210002
- 088A0003
- 088A0004
LU-LU session terminations (UNBIND) for the following reasons:
- Normal end of session (TYPE=X'01')
- CLSDST PASS (TYPE=X'02')
- Session parameters that are not valid (TYPE=X'06')
- Other UNBINDs between X'01' and X'06'
- Format or protocol error (TYPE=X'FE')

A session termination for any reason other than those reasons described previously is handled as an abnormal session termination and causes the deletion of any VTAM-managed dynamic USERVAR associated with that session. Following are examples of abnormal terminations:

Requests for forced termination which, like requests for conditional or unconditional termination, can come from operators, SLU application programs, or terminals.
LU-LU session terminations, including:
- VR INOP (TYPE=X'07')
- Route extension INOP (TYPE=X'08')
- LU failure (TYPE=X'0C')
- Cleanup termination, such as V NET,INACT (TYPE=X'0F')
- Gateway node cleanup (TYPE=X'11')
Session setup failures other than those previously described (such as failure to find the destination LU after using a dynamic USERVAR to determine the application program name). In such cases, VTAM deletes the dynamic USERVAR and tries the session initiation again using the USERVAR name to determine the current value of the user-managed USERVAR.

Whenever the active application program in an XRF complex fails, notification of the session failures is sent to the SSCPs of the session partners, thereby causing them to reset their dynamic USERVARs. In the host of the XRF active application program, VTAM deletes all USERVARs that reference the failing application program to prevent future USERVAR searches from using a USERVAR that references the failing application program.

If a backup session already exists, an alternate application program sends a switch request to the NCP to takeover the sessions. The XRF takeover can be initiated before VTAM even knows that the active application program is failing. The VTAM first awareness of such a takeover is the receipt of a session ended notification having a specific session termination reason code (X'13'), which indicates that the primary session terminated because of an XRF switch. At a remote SSCP, such session terminations are handled as abnormal session terminations. At the SSCP of the failing active application program, however, the SSCP also does the following actions:

Marks the application program as "not enabled for sessions" to prevent any further session establishments
Deletes the USERVAR that is associated with the session that is ending