On 16 December 2014 at 03:51, <[email protected]> wrote: >>> I guess that I really want LARLE to set AR2 as well a GPR2. > > Not - not realy- There is no need for it. You need an AR with zero in > it if your intent is to move some constants from non AR based stuff to > a dataspace (while in AR mode) > > 14 and 15 come in handy (they are very transient and are extrem > likely to have a zero)
But beware that some MVS services (notably WTO) use some subset of ARs 0-1 and 14-15 as work registers, and return them containing non-zero values. It's documented, but it changed some time back, and caused trouble for code that inadvertently relied on their not being changed. Worse, if the WTO is there for diagnosis only, the code breaks when you enable tracing/logging but runs fine otherwise. Tony H.
