On 11 April 2017 at 16:26, Paul Gilmartin < [email protected]> wrote:
> If a program touches a page that was never GETMAINed no error > occurs; simply a page slot is allocated up to the limit of the REGION > parameter. Conversely, on FREEMAIN the page slots are not released. > I really don't think so... It's easy to experiment. > > Programmers with a strong UNIX/C background loathe this. > Maybe because they believe in all kinds of mainframe myths. The machines are run by nerdy looking men in white lab coats, with ties mandatory, I've heard. And everything requires punch cards to get any work done. They are accustomed to do needed malloc()s up front and handle errors at > that > point; their code is not designed to handle out-of-storage conditions > that occur unexpectedly, later when a page is touched. > Sounds like, uh z/OS. > > From the other point of view, traditional OS programmers are accustomed > to code enormous fixed GETMAINs in case they need the storage years in > the future -- just adjust the REGION and the program works again. > Not quite sure what you're saying. The old, constrained-memory technique was usually to issue a variable (Vx) GETMAIN, specifying the minimum required size as the low bound, and the maximum useful as the high. Then the system returns the actual amount obtained, or a return code or abend if it can't deliver even the minimum. In pre-MVS systems, the REGION= was a hard control on the max; in MVS, REGION= turned into a per-use limit on Vx GETMAINs, with the hard limit being the available private area. In more recent systems there are exits that can limit most of these values, and of course there is split BTL and ATL storage, not to mention ATB. > > Culture clash. > Perhaps, but it's unwise to ascribe to the "other" culture incorrect facts. Tony H. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
