Peter Relson wrote: >For what it's worth, and I might be wrong about this, I thought that the >clock was typically recommended to be set to UTC. >And by subtracting CVTLSO from the STCK value you get to GMT, not to UTC >(UTC differing from GMT by leap seconds). >And you get to LOCAL by taking GMT and subtracting CVTLDTO. Yes, you are wrong about this. GMT and UTC are essentially the same. GMT changed to UTC (Coordinated Universal Time) on the last second of 12/31/1971. Main difference is UTC uses leap seconds to synchronize with International atomic time (TAI). There have been 25 leap seconds since 1972. UTC was 10 seconds behind in 1972 when UTC started so UTC is 35 seconds behind TAI time.
Customers that require precise time and are using STP to synchronize to an NTP server need to use leap seconds. This means the CEC's TOD (STCK time) is NTP server time (UTC time) plus leap seconds. The reason for this is so that the CEC's TOD (STCK time) is correct when a leap second is introduced. If leap seconds are not used so that the CEC's TOD (STCK time) equals UTC then when a leap second is introduced the CEC's TOD will be out by 1 second and STP will take 7 hours to steer the 1 second adjustment. George Kozakos z/OS Software Service, Level 2 Supervisor ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
