I have question then....

I inherited some code..it's called passed a value for a storage obtain...
Before the obtain, they go into mode=sup, "storage
obtain,length(value),sp=231,loc=any", then back into mode=prog. Is this the
old way of setting key zero or a piece of storage ?

Scott

On Sunday, July 12, 2015, Rob Scott <[email protected]> wrote:

> In one word - "carefully".
>
> Treat every instruction that you execute in key0 as being a candidate to
> cause the next unscheduled IPL.
>
> I would advise to straddle the code that *actually* requires key0 with a
> "save current key, go to key0" and then a "restore saved key" sequence - I
> typically put this in a macro.
>
> Make sure that your recovery routines are aware that this code can
> key-switch and let them restore the environment cleanly.
>
> Always be aware of the key of your caller and use it to read and write
> data owned by them - MVCDK and MVCSK are your friends (also good candidates
> for macro encapsulation).
>
> SAF protect any services that you provide to problem state callers.
>
> Never return to your caller with any changes to their execution authority.
>
> Test your code (on a test system) with the "dirty regs" and "dirty
> getmain/freemain" diagnostic traps.
>
>
>
> -----Original Message-----
> From: IBM Mainframe Discussion List [mailto:[email protected]
> <javascript:;>] On Behalf Of Scott Ford
> Sent: Sunday, July 12, 2015 11:57 AM
> To: [email protected] <javascript:;>
> Subject: Re: SYSTEM KEY Programming Was: IVSK and SPKA
>
> With all the discussion, what's the safest way to use key=0 , if it is
> required ?
>
> Scott
>
> On Sunday, July 12, 2015, Tom Marchant <
> [email protected] <javascript:;>> wrote:
>
> > On Sun, 12 Jul 2015 11:29:01 -0400, Steve Thompson  wrote:
> >
> > >And hasn't support for DAT OFF (V=R) been dropped? Only the DAT OFF
> > >nucleus actually runs DAT OFF now?
> >
> > V=R doesn't mean DAT off.
> > Just that virtual addresses map to the same real addresses.
> >
> > I've never seen anything that ran V=R, but ADDRSPC=REAL is still
> > documented.
> >
> > --
> > Tom Marchant
> >
> > ----------------------------------------------------------------------
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> >
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