From the point of view of job management, the system no longer needs to be shut down and restarted when switching between summer and winter time:
Job management works internally with UTC time, which is wholly incremental and which does not recognize time changes. Externally, job management uses the time set for the system installation, known as the system time, which is based on local time (LT, the legally valid time at the place of installation). This means that the user is always able to work with the official local time.
A precondition for correct time switching by job management is the correct system parameter files with specifications for time conversions (see "System time control (GTIME)"). Time specifications are thus always interpreted as legally valid local time, regardless of time changes, e.g. start times for jobs with deadlines.
Consistent interpretation of time specifications as official time also results in a change in the way repeat jobs with the “DAILY” and “WEEKLY” attributes are started: the start time for the daily or weekly repeat is determined when such repeat jobs are accepted. This start time is now consistently interpreted as official time. Thus, for instance, a job that was executed daily at 5 p.m. during summer time will also be started daily at 5 p.m. after the change to winter time.