>From an z/architecture point of view a program interrupt code could be 
>generated by referencing a 64-bit address which was higher than the installed 
>amount of memory. But to get an interrupt code 0005 on a z/OS system today is 
>significantly more difficult I think.

Lennie Dymoke-Bradshaw
https://rsclweb.com 
‘Dance like no one is watching. Encrypt like everyone is.’

-----Original Message-----
From: IBM Mainframe Discussion List <[email protected]> On Behalf Of 
Tony Harminc
Sent: 27 April 2022 22:57
To: [email protected]
Subject: Re: EXTERNAL: CIBXUTOK fetch protected

On Wed, 27 Apr 2022 at 16:20, Paul Gilmartin 
<[email protected]> wrote:

> A Historian told me long ago that Addressing exceptions were so rare 
> before DAT that MVS/XA elected to reflect 0005 as S0C4 for 
> compatibility with existing code.

This sounds oddly backwards. Before DAT, i.e. MVT et al, addressing exceptions 
were common enough on any but a fully kitted out machine - and machines with 
16MB were rare.

But I'm not convinced that S0C5 even exists on any MVS or later OS/360 
descendent. How would you provoke one? If you're running V=V, you'll get a page 
or segment fault (0010 or 0011) or some other DAT-related failure, and I think 
those are all turned into S0C4s if unresolved.
Surely nobody is running V=R in 2022 (does z/OS even support it?), so I'm not 
sure how you'd get a 0005 - let alone a S0C5 - for referencing non existent 
storage.

Tony H.

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