Registers at entry

The mainline exits have these register contents on entry:
Register
Contents
0
Address of the exit parameter block (EXPB)
1
Address of a parameter list
2–12
Not applicable
13
Address of register save area
14
Return address
15
Entry point address
The service exits have these register contents on entry:
Register
Contents
0
Address of the exit parameter block (EXPB)
1
Address of a parameter list
2–13
Not applicable
14
Return address
15
Entry point address
The CKDS entry retrieval installation exit has these register contents on entry:
Register
Contents
0
Not applicable
1
Address of a parameter list
2–12
Not applicable
13
Address of register save area
14
Return address
15
Entry point address
The conversion program, single-record, read-write, and KGUP exits have these register contents on entry:
Register
Contents
0
Not applicable
1
Address of a control block (CVXP, RWXP, or KGXP, depending on the exit)
2–12
Not applicable
13
Address of register save area
14
Return address
15
Entry point address

The particular control blocks that are passed through register 0 or register 1 are described with each exit.

Parent topic: Entry and return specifications