On Fri, 30 Aug 2013 19:56:00 +0000, Ward, Mike S wrote: >Save areas and such would have to be twice as large to hold >the registers. Can someone please shed some light on this?
It is more complicated than just making the save area twice as large. The reason is that there are still a lot of programs that only use the low halves of the registers and save the registers the old way. Lots of system services are like that. If they weren't, an old program wouldn't be able to call them. If you want to know about the new save area formats, it is documented in chapter 2 of the Assembler Services Guide, titled "Linkage Conventions." When you look for the manual, use the one for z/OS release 12 or higher. Peter Relson made extensive changes to the chapter for the release 12 edition of the manual in order to clarify it. Most normal programs that use the high halves of the registers would use either F4SA (if they are only called by 64-bit programs) or F5SA (if they are, or might be, called by a 32-bit program). -- Tom Marchant
