User Exit 12

Purpose

This exit point controls partner LU security. It executes a user‑written exit routine that verifies a given user's authority to transfer data to and from a particular LU. The following are the possible results of the verification:

The user is given access to the designated LUs.
The user is denied access to the LUs.
The user's right to access the LUs is referred to the security package.

Module Name and Entry Point

The default module name and entry point for this exit is XCOMEX12. The default module name can be overridden by specifying the load-module name in the Default Options.

How to Enable

Specify EXIT12=YES | Load-module name in the Default Options to enable this exit.

Calling Module

The module XCOMTRGT calls this exit.

Entry Method

This exit is a branch entry.

Required DSECT

EX12PLST is the required DSECT.

Addressing Mode at Entry

The addressing mode at entry is 31.

Registers at Entry

The following registers are available at entry:

R0: Undefined
R1: Address of EX12PLST
R2 to R12: Undefined
R13: Address of register save area
R14: Return address
R15: Entry point address

Registers at Exit

The following registers are available at exit:

R0 to R14: Undefined
R15: Return code

Valid Return Code

The only valid return code is 0 for a normal return.

0: Allow access immediately
4: Let the security package make the decision
8: Deny access immediately

Sample Program

The following is a sample program using this exit:

CAI.CBXGSAMP(XCOMEX12)

Note: In cases where a transfer causes the server to create a session due to GETSESS=YES, Exit 12 is called once before session establishment and once before the transfer is performed. The exit is also called before each transfer restart.