On Sat, 18 Jul 2026 15:59:06 -0500 Paul Gilmartin <[email protected]> wrote:
:>A step in deriving GMT from TOD is to subtract CVTLSO. I assume the TIME :>macro does this. And user processes are made non-dispatchable curing a :>leap second for timestamp consistency. :>But I imagine a remaining race condition. If CVTLSO is accessed and STCK :>is issued on opposite sides of a leap second, the derived GMT can be in :>error by nearly a second. That could be avoided by: :>TRY fetch CVTLSO :> STCK :> compare fetched value to CVTLSO :> BNE TRY :>Two additional instructions for a hazard that occurs only every few months. :>Does TIME macro do that? Is there a better way? :> :>Good practice might be to store not GMT but TOD in critical data bases :>and to derive GMT only for reports. That requires CVTLSO at the time of :>the event. That's in the PoOps, but can report generators be updated :>in timely fashion? :>There's an active discussion of leap seconds and the Sunshine Protection Act on :><https://lists.iana.org/hyperkitty/list/[email protected]/> As STCK(E) does not perform a synchronization function, the only compare possible that would cause a sync would be CS (which requires Key 0). I guess you could issue some other instruction that does a sync, but I wonder if this is worth it. -- Binyamin Dissen <[email protected]> http://www.dissensoftware.com Director, Dissen Software, Bar & Grill - Israel ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
