Register contents on program call
The following table provides an overview of register contents as supplied by the calling program (before passing control to the called program).
Register number | Contents |
0 | Number of parameters |
1 | Start address of the parameter address list |
2 - 12 | Undefined |
13 | Start address of the save area of the calling program |
14 | Address of the return point to the calling program |
15 | Address of the entry point in the called program |
PM | Program mask: value of PCD field “program mask” (default X'0C') |
Register contents on return to the calling program
The following table provides an overview of register contents as supplied by the called program when returning control to the calling program.
Register number | Contents |
0 and 1 | Return values of integer functions (or undefined) |
Floating-point register 0 | Return values of floating-point functions (or undefined) |
2 - 14 | As in table above |
15 | Undefined |
PM | Program mask: value from PCD field “program mask” |