Exit-list (EXLST) exit routines

These are special-purpose exit routines that VTAM® schedules when appropriate, such as on receipt of a CINIT request as a result of a logon or initiate request. The exit-routine addresses (entry points) are specified in an exit list created with the EXLST macroinstruction.

A program can define more than one exit list by using multiple EXLST macroinstructions. However, an ACB can point to only one exit list at a time.

An exit list can be specified in an ACB and thus can be used by VTAM when an exit-routine event occurs for any session with the program, including those sessions that VTAM sets up to support LU 6.2 conversations.

The ATTN exit, which is an EXLST exit, handles LU 6.2-specific event notifications. VTAM schedules the ATTN exit when one of the following conditions occurs:

The application program receives an FMH-5.
VTAM processes a CNOS request from a partner LU or an operator command, and new session limits are established.
The last session or each session of a mode name group is terminated.

For details on this exit routine, see Using the ATTN exit.

Not all the exit routines that application programs can supply have meaning for LU 6.2 functions. The names of the already-existing special-purpose exit routines applicable to LU 6.2 and the events that cause them to be entered are summarized in Table 1.

Table 1. Special-purpose exit routines applicable to all session types
Exit Routine Name	Event
LERAD	A logic error has been detected for an RPL-based request.
LOGON	An application program is being requested to establish a session as a primary logical unit.
LOSTERM	A session with an application program has been terminated or disrupted, or a conditional terminate request for a session has been received.
RELREQ	Another application program has requested a session with a logical unit that is presently in session with this program, and the logical unit is at its session limit.
SCIP	A session-control request has been received. This exit is only scheduled for LU 6.2 sessions when a BIND request is received for the application program. The other types of session-control requests that this exit deals with are handled by VTAM for an LU 6.2 session.
SYNAD	An error other than a logic error has been detected for an RPL-based request.
TPEND	The VTAM operator shuts down the network or this application program, or VTAM halts or abends, or a VTAM application program is being taken over.

The existing exit routines not applicable to LU 6.2 sessions are:

DFASY
NSEXIT
RESP

For more details on the special-purpose exit routines, see Using exit routines.