The TMON for VTAM address space must be shut down when setting the GMT adjustment forward. To stop the TMON for VTAM address space, issue the MVS P command or logon to TMON for VTAM and issue the SHUTDOWN command. The TMON for VTAM address space must be shut down when setting the GMT adjustment backward. To stop the TMON for VTAM address space, issue the MVS P command or logon to TMON for VTAM and issue the SHUTDOWN command.
Considerations Regarding ASG-TMON for VTAM when Changing the GMT Adjustment Factor
Setting the GMT adjustment factor forward (Standard Time):
After setting the GMT offset forward you can immediately re-start the TMON for VTAM address space.
Data Considerations:
You can use the LFS logs immediately without clearing them. There will be a time gap in the data for the time period the clock was set forward.
After setting the GMT offset backward you should wait until the clock has re-gained the time it was set back before re-starting the TMON for VTAM address space.
Data Considerations:
If you start the TMON for VTAM address space before the clock re-gains the setback time, duplicate timed log records will be written to the LFS logs. The overlapping log records may show increased statistics for a particular hour or invalid summary data when building history files.