It loosely looks like a savearea chain with some additional detail, expanded on stack.
Presently Im looking into XL documentation. If someone knows a resource/doc, where ABI is specified, or some comments on the subject, please share.
Joined: 30 Nov 2013 Posts: 812 Location: The Universe
It appears to me to be the Language Environment model. In turn, this model goes back to 1960s common practice for reenterable programs. In this model, reg 13 points to a "standard" 72 byte register save area followed by a work area.
For better or worse, many working Assembler programmers have abandoned this model. Reg 13 still points to a save area, but a second register points to a work area shared by, at least, all the internal functions in a single program.
Yes, I know any CS101 alumni will point out this model is flawed, but those CS101 professors are seldom working Assembler programmers, and they look down on us as vermin.