I can't believe how often the old chestnut about running in key zero versus user ket comes up. There is nothing inherently risky running in key zero - presuming of course that you're not a cowboy coder who fails to validate input and output areas. Store instructions only go where you point them. The overlay bogey is shorthand for sloppy coding.
As for running in key 8 in an SRB, it is certainly NOT necessary (there are mixed key instructions for safely moving data to/from caller storage) and furthermore it is actually a bad idea for a number of reasons. First, it is a fairly unusual condition for an SRB to run in - potentially causing serious astonishment (I.e. Generally a bad idea) in called code, but here's my personal favorite dingbat reason... Running an SRB in a user key is a probable integrity violation if the SRB uses user key storage for work areas, save areas etc. So the ostensible "ooh it is safer in user key" is just a crock. For the record, I have never once run an SRB in anything but a system PSW key, and wouldn't. There's just no reason to > Date: Thu, 24 Jun 2010 20:37:29 +0300 > From: [email protected] > Subject: Re: Data exception in SRB routine > To: [email protected] > > On Thu, 24 Jun 2010 11:53:40 -0500 Chris Craddock <[email protected]> > wrote: > > :>> > :>> Got a data exception with reason code 7 for an STD instruction in an > :>> SRB routine : > :>> 00000000 *PGM 007 078C2000 D43615B6 00040007 00000000 > :>> The instruction STD FR10,... > :>> As far as I see , the control reg 0 , bit 45 (AFP control) is on . > :>> (It is a z9 S07) > > :>An SRB routine running in PSW key 8?!? WTF? > > Nothing at all wrong with that. It knows that the areas that it needs to > modify are in key8. > > It is a quite bad practice to run in key0 when it is not needed. All sorts of > bad overlays can happen. > > -- > Binyamin Dissen <[email protected]> > 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.
