Register 1 |
The address of an MFX parameter list. |
Register 13 |
The address of a register save area. For exits called with the 24-bit or 32-bit parameter list, the save area is 19 words, where the first 18 words are a Format 0 save area that can be used to save registers, and the 19th word can be used to pass information between Assembler exits. For exits called with the 64-bit exit parameter list, the save area is a 36 word Format 4 save area. The Format 0 and Format 4 save areas are defined by the IHASAVER Assembler macro. |
Register 14 |
MFX’s return address, in the low-order address bits of the register. The high-order bit(s) may have undefined contents. |
Register 15 |
The address of the entry point of the exit routine, in the low-order address bits of the register. The high-order bit(s) may have undefined contents. |
The standard operating system conventions apply to register usage. Exit routines must save and
restore Registers 0 and 2-14. The sort/merge places these contents in Register 1 and
13-15 for use by the exit routine when it takes control.