I have to wonder how significant the CPU time saving from using three MVC instructions versus 104 ZAP instructions is when weight against the thousands of AP instructions that are being performed against those seven digit pack decimal counters.
Keven Hall > On Nov 29, 2025, at 22:31, 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 >>
