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.