On Tue, 27 Nov 2012 13:17:11 -0600, Andy Wood <[email protected]> wrote:

>On Mon, 26 Nov 2012 10:01:38 -0600, Mark Zelden <[email protected]> wrote:
>
>>. . .  Things
>>like PSA overlays, UCB overlays etc.  Of course over the years IBM has added
>>lots of code and features to repair critical control blocks and there are 
>>captured
>>UCBs etc., so it less frequent. . . .
>
>The introduction of captured UCBs was a backward step from a system 
>reliability point of view, as it increased the chances of a UCB being 
>overlaid, and could make it very difficult to catch the culprit. The much 
>later Captured UCB Overlay Protection restored the reliability status quo.
>

Thanks for the clarification.  That was what I was referring to.  Yes, captured 
UCBs 
are ancient at this point. Without researching,  I'm pretty sure it was MVS/ESA 
5.2, but
it could have been MVS/ESA 5.1 or OS/390 R1.  

--
Mark Zelden - Zelden Consulting Services - z/OS, OS/390 and MVS       
mailto:[email protected]                                        
Mark's MVS Utilities: http://www.mzelden.com/mvsutil.html 
Systems Programming expert at http://expertanswercenter.techtarget.com/

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