The SCIP exit routine, if present, is scheduled when a BIND is received. If the BIND is for an LU 6.2 session, the application program must use the APPCCMD CONTROL=OPRCNTL macroinstruction to respond to the session request. Specifying QUALIFY=ACTSESS responds positively to the session request. Specifying QUALIFY=DACTSESS rejects the session request.
When the SCIP exit is driven, register 1 contains the address of a parameter list. Word 4 and word 5 of the parameter list have specific uses for LU 6.2 application programs.
Word 4 of the parameter list contains the address of the session parameters of the BIND in a format that can be examined by using the ISTDBIND DSECT.
Word 5 of the parameter list contains the address of a read-only RPL. The RPLAREA field of the read-only RPL contains the address of a read-only copy of the BIND. To examine the BIND request unit as VTAM® received it, use the RPLAREA field to access the read-only copy of the BIND.
The RPLAAREA field of the read-only RPL points to the beginning of the control vectors within the BIND area (no RPL extension is provided).
The application program also can determine whether the BIND is an LU 6.2 BIND by testing the RPLVACS bit in the read-only RPL. If the bit is set on, the application program should use the APPCCMD macroinstruction to respond to the session request. For more information on the SCIP exit, refer to z/OS Communications Server: SNA Programming.
After a session is established as a VTAM-controlled LU 6.2 session, the SCIP exit routine is not scheduled again for the session. The session control requests CLEAR, RQR, STSN, and SDT are not allowed on an LU 6.2 session.
The application program uses the SETLOGON macroinstruction to regulate when the SCIP exit routine is scheduled. The SETLOGON macroinstruction functions exactly as described in z/OS Communications Server: SNA Programming.