Registers on Entry to the Pre-ACS Exit Routine

When the pre-ACS exit gets control, the general-purpose registers have the following content:

Register: Contents
0: Not applicable
1: Address of the parameter list mapped by IGDACERO.
2-12: Not applicable
13: Address of register save area
14: Caller's return address
15: Address of the exit's entry point

Note: Because this routine is called before ACS routines, some variables, such as Data Class, will not have been set. JCL parameter values should be available.