On 4 April 2011 08:01, Joe Owens <[email protected]> wrote: > One question occurs - must I now use extended save areas, as I am doing > something to the top halves of the GPRs, or will the system take care of > that for me? (There are no amode 64 progs on the calling chain).
Perhaps it's obvious, but... You don't need to do anything if you are merely using the 64-bit GPRs for calculation, i.e. the system will not munge the high halves just because there is an interrupt and you lose control, no matter what addressing mode you are in and what save area scheme, if any, you use. You need to worry only if you want to call a routine (your subroutine or a system service) and have a 64-bit value in a GPR that you want preserved. It's almost certainly easier just to make sure such values are safely stored before you make the call than it is to update the save area scheme. Tony H.
