I'm not sure I understand how that would work.

Brian

On Sun, 30 Nov 2025 19:43:16 -0500, Steve Thompson <[email protected]> wrote:

>Suppose you create an INIT variable that is the size of what you
>need, have it built using all DC PL4'0' (or whatever init values
>are needed) and then do an MVCL from the INIT to the working
>area? Most of the overhead in that case will be in the HLASM as
>opposed to the program.
>
>Just a thought.
>
>Regards,
>Steve Thompson
>
>On 11/30/2025 1:03 AM, Brian Westerman wrote:
>> Thank you!!!  This is exactly what I was looking for.  I had thought the 
>> limit was a single byte, but I tried this and it works perfectly.  In 
>> initial testing it seems to load quite a bit faster.  I'm going to add some 
>> code to compare the two (before and after) for CPU overhead.  But this seems 
>> to be pretty good.  It's definitely a lot less code to go through.
>>
>> On Sat, 29 Nov 2025 23:30:39 -0500, Steve Smith <[email protected]> wrote:
>>
>>> MVC "ripple" initialization isn't limited to 1-byte.
>>>   ZAP   P1,=P'0'
>>>   MVC  P2(256),P1  Init P2-P65
>>>   MVC  P66(156),P65 Init P66-P104
>>>
>>> Check my math...  better yet use EQU and DC to do the math.
>>>
>>> sas
>>>
>>> On Sat, Nov 29, 2025 at 10:35 PM Brian Westerman <
>>> [email protected]> wrote:
>>>
>>>> Hi,
>>>>
>>>> I have a program in which I have 104 PL4 fields tht are used for various
>>>> counters, and when the program starts it spends a significant amount of
>>>> time initializing all of those fields to zero.
>>>>
>>>> we used to use ZAP field,=PL4'0' and then I found an entry (on the web)
>>>> that said it would be "slightly" faster to use MVC, so I changed it to 104
>>>> MVC filed,=PL4'0'.
>>>>
>>>> Is there not a quicker way to do this?  I know that I can ripple the first
>>>> byte of a field for up to 256 bytes with a single instruction, but can that
>>>> same type of thing be done with a 4 byte packed field?
>>>>
>>>> If not, is there a quicker way to initialize these fields without doing
>>>> each one separately?
>>>>
>>>> Thanks for any tips.
>>>>
>>>> Brian
>>>>

Reply via email to