Register conventions

Register values that apply at entry to the exit program.

• Register 1 contains the address of the exit parameter list.
• Register 13 contains the address of the register save area. The exit program saves and restores the registers that it modifies, using the save area addressed by register 13.
• Register 14 contains the return address that the exit program branches to when it completes its work.
• Register 15 contains the entry address of the exit program.