Tom M wrote: > This is documented in chapter 2 of the Assembler Services Reference.
Tom meant the Assembler Services Guide. And he probably feels bad about that mis-reference because he helped write that section. This is the Linkage Conventions section. If you're saving only the low halves of the GRs, an 18-word save area provided by the caller is recommended. If you're saving only the 64-bit GRs, a 36-word save area is recommended. If you're also saving access registers, the standard convention is to use the linkage stack (there are mapped approaches that use a larger save area that can hold both GRs and ARs). Do note that there are limits to the number of entries you get by default on the linkage stack. And keep in mind that ESTAE-type recovery routine retry is sensitive to the linkage stack level when the routine is established. Peter Relson z/OS Core Technology Design
