The session management exit routine invokes this function during session initiation and during SSCP takeover. Using this function, the session management exit routine determines whether to allow a session. If initial authorization for INIT OTHER CD is selected during begin function processing, the exit routine invokes initial authorization for both CLSDST PASS (which uses INIT OTHER CD) and normal initiation processing.

If initial authorization for LU session takeover is selected during begin function processing, the exit routine invokes initial authorization for LU session takeover if the sessions being taken over were established using extended BIND protocols.

In addition, for normal initiation processing, the initial authorization function can authorize session setup and request that the secondary authorization function be scheduled if session initiation fails.

For SSCP takeover, the initial and secondary authorization features provide equivalent function.

If the initial authorization function is not selected during begin function processing, VTAM® defers authorization to the secondary authorization function. If the exit routine does not process secondary authorization either, VTAM authorizes the session.

The authorization process is slightly different for CLSDST PASS (INIT OTHER CD) processing. The secondary authorization function is not driven for CLSDST PASS processing when neither the PLU nor the SLU are in the initiating LU's host; therefore, the initial authorization function cannot defer session authorization for INIT OTHER CD. This limitation applies only to the portion of the new session establishment path that is processed under the INIT OTHER CD, that is, that portion of the path between the initiating logical unit (ILU) and either the new PLU or the SLU. For the portion of the session establishment path between the new PLU and the SLU (inclusive), both initial and secondary authorization occur without limitation.

For CLSDST PASS processing, certain parameters in the initial authorization parameter list point to information about the initiating logical unit (ILU). The OLU and DLU gateway information vectors contain information about the ILU and SLU rather than the OLU and DLU. The ILU resource identifier control (RIC) vector provides the ILU name, the ILU network ID, and its owning SSCP name during CLSDST PASS processing. The ILU and SSCP names provided in the vector are the real names used by the application program; no translations occur on these names.

The ILU RIC vector is present only with CLSDST PASS (third-party initiated sessions). Even with third-party initiated sessions, the ILU RIC vector is present only when the SSCPs on the session establishment path are at a level that supports the provision of this data. When referencing the ILU RIC data, the pointer to the data should be examined to determine whether the information is available for use. The setting of the high-order bit in the last parameter indicates the end of the parameter list; consider this when determining the presence of the ILU RIC.

For CLSDST PASS sessions, the name of the resource issuing CLSDST PASS is supplied to the initial authorization function in the session initiation user data field.

Table 1 shows the initial authorization function parameter list pointed to by register 1. The parameters are described in Parameter descriptions.

1. This offset should be tested for zero before usage. When the offset is nonzero, it represents a pointer to the TCP/IP information control vector. This vector provides the IP characteristics of a TN3270 client associated with the SLU resource.