LOGON exit routine

VTAM® schedules the LOGON exit routine to inform the application program that it should establish a session in which it acts as the PLU. VTAM schedules the LOGON exit when a CINIT request is received unless:

The ACB is opened with MACRF=NLOGON.
The ACB is opened with MACRF=LOGON, but SETLOGON OPTCD=START has not been issued (CINIT is queued).
The CINIT results from the application program issuing OPNDST OPTCD=ACQUIRE.
The application program has a matching outstanding OPNDST OPTCD=ACCEPT to accept that CINIT.
A SETLOGON OPTCD=HOLD request holds the exit (CINIT is queued).

If a CINIT has been queued, the LOGON exit routine is scheduled when SETLOGON OPTCD=START is issued.

The LOGON exit parameter list provides the name of the SLU and the CID of the established session. These items can be used to identify the CINIT request to be accepted with OPNDST OPTCD=ACCEPT or rejected with CLSDST.

The exit parameter list provides the user-request correlator. Unless the application program initiates the session with the SIMLOGON macroinstruction, this field is 0. If the application program uses the SIMLOGON macroinstruction, the field contains the contents of the NIB's USERFLD field at the time SIMLOGON is issued. The field also provides a means of determining whether SIMLOGON caused the CINIT request and, if so, which one. A read-only RPL is also provided to the exit routine. The AREA field in this RPL points to a read-only copy of the CINIT request. The RPL RECLEN field contains the length of the CINIT request. Refer to SNA Formats for a description of the CINIT request.

Because different network components manage the network addresses and the addresses can vary, the application program should ignore any network addresses that appear in the CINIT request unit.

Certain information can appear in control vectors appended to the CINIT RU.

Vector: Description
X'0D': Class-of-service and virtual route list
X'0E': Network-name control vector or network-qualified name of the PLU if present
X'0E': Network-name control vector or network-qualified name of the SLU if present
X'15': Network-qualified address pair control vector
X'2C': COS and TPF control vector
X'2D': Mode-name control vector
X'2F': Model-terminal-information control vector
X'59': Session authorization data control vector
X'5F': Extended fully qualified PCID control vector
X'60': Fully qualified PCID control vector
X'64': TCP information control vector
X'66': Data compression control vector

For a detailed description of these control vectors, refer to SNA Formats.

The LOGON exit routine can include a procedure to obtain a copy of the information in the CINIT request. This information can be interrogated for session parameters and also for the logon mode name and the class-of-service (COS) name. For example, the logon mode name must be saved by the application program for use with a subsequent CLSDST OPTCD=PASS macroinstruction if the same COS is to be used in the second session. A procedure for obtaining the session parameters is demonstrated in Example 1 of Examples of how an application program processes session parameters. Example 2 of the same section demonstrates a procedure for obtaining the logon mode name.