On 12 February 2014 14:21, Jim Mulder <d10j...@us.ibm.com> wrote: > When a length of 0 is requested on GETMAIN or STORAGE OBTAIN, > VSM treats this as a successful request, and returns an address of 0. > In my opinion, this was a poor design choice, made long before my time, > and I have seen it lead to diagnosis confusion like this several times > over the years. I would have preferred to abend when a length of 0 > is requested. But it has worked this way since at least MVS/370, > and maybe even long before that, so for compatibility reasons, > we do not change it.
I object far more to returning an address of 0 than to accepting a length of 0 on the request. To be sure, you are allowed to store no more than 0 bytes in your obtained area, so the 0 address sounds reasonable, but some instructions are allowed by the architecture to recognize access exceptions in the case where no data is stored, e.g. STCM with a zero mask. So to be consistent, a non-zero address with appropriate access setup (primarily key) should probably be returned. Now if you ask me how I would prioritize this requirement... Tony H. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
