On Mon, 12 Jun 2017 00:31:28 -0400 Randy Hudson <i...@panix.com> wrote:
:>In article <2376347398828975.wa.paulgboulderaim....@listserv.ua.edu> you write: :> :>> Point taken. But it's not clear why the designers chose to allow a program :>> to be both modifyable and reloadable. This leads to dreadful unpredictability: :>> Behavior may differ depending on whether the program has been reloaded. :>> OK. Initialization code may set a flag (in each page?) that will be cleared by :>> a reload. Critical code paths may check (before and after) that the flag remains :>> set and re-initialize if it's found cleared. And the documentation should :>> conscientiously mention the need to do this. Ugh! :>The REFR attribute has existed since MVT version 19 or so. Core storage :>then was really core storage... toroidal ferrite cores threaded on wires, at :>a cost of a dollar a bit, or more. :>Saving a few bytes is sneered at as false economy, now. It wasn't, then. :>A refreshable load module might have inititalization code that needs to be :>run only once per time it's loaded, with that init code overwritten for :>scratch storage afterward. If the module's space is needed, the whole thing :>gets overwritten. Later it can be refreshed, and the initialization re-run. :>Or, a module might contain a dynamically reorganized search table, such as a :>move-to-front table. That's storage modification, and it's hard to make it :>re-entrant on a 360/65 with only TS as a locking mechanism. But it can be :>refreshable, reloading the initial configuration each time. That would only allow the refreshable module to be reloaded if it is started at the entry point. It cannot be refreshed while it is in the middle of being executed. -- Binyamin Dissen <bdis...@dissensoftware.com> http://www.dissensoftware.com Director, Dissen Software, Bar & Grill - Israel Should you use the mailblocks package and expect a response from me, you should preauthorize the dissensoftware.com domain. I very rarely bother responding to challenge/response systems, especially those from irresponsible companies. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
