CICSPlex SM time zone attributes

CICSPlex® SM uses three attributes to facilitate timing services. These attributes and their available values are:

Time Zone
B through Z
Start of changeTime Zone OffsetEnd of change
Start of change0 through 59 minutesEnd of change
Start of changeDaylight Savings in effectEnd of change
Start of changeYES or NOEnd of change

These attributes are used to help CICSPlex SM:

These attributes are specified for the following CICSPlex SM definitions:

CMAS
Using the CICSPlex SM EYU9XDUT utility (as described in the CICS® Transaction Server for z/OS® Installation Guide manual).
Start of changeCICSplexEnd of change
Start of changeUsing the CICSplex definition view (as described in Managing CICSplex definitions using the Web User Interface)End of change
CICS system
Using the CICSSYS (as described in CICS system definitions) or MAS views
Start of changeTime periodEnd of change
Start of changeUsing the Time period definition view (as described in Managing time period definitions using the Web User Interface)End of change

Attribute definitions

The three attributes that facilitate timing services are defined as follows:

Time Zone
CICSPlex SM uses the international standard for time zones. This consists of 24 zones around the world, separated in time by 60 minutes each. The standard for these zones is the prime meridian, and time at the prime meridian is referred to as Greenwich Mean Time (GMT).

The area having Greenwich Mean Time is referred to as time zone Z. The next time zone to the east, where time is 60 minutes (one hour) ahead of GMT, is time zone B. When GMT is 12:00 noon, the time in time-zone B is 13:00. The next time zone to the east, 120 minutes (two hours) ahead of GMT, is time zone C. For each time zone to the east, time advances one hour, until time zone M, where local time is 12 hours ahead of GMT. Time zone M is at the international date line.

The next time zone east, time zone N, is (like time zone M) separated from GMT by 12 hours. However, because it is considered to be on the opposite side of the international date line from time zone M, it is 12 hours behind GMT. Similarly, the next time zone east, time zone O, is 11 hours behind GMT. When GMT is 12:00 noon, the time in time zone O is 01:00. For each time zone to the east, one hour is subtracted, until time zone Y, which is one hour behind GMT.

Note that there is no time zone A.

Time Zone Adjustment
Some locations around the world have implemented times that are different from GMT by times that are not 60 minute multiples. For situations such as these, CICSPlex SM uses a time zone adjustment. To define the time zone of such a location to CICSPlex SM, the time zone of the next lowest 60 minute multiple is used, and the difference, in minutes, between the 60 minute multiple and the location’s time is entered as the Time Zone Adjustment. For example, when the time is 13:00 in London, England (this is GMT, or time zone Z), it is 22:00 in Tokyo, Japan (time zone J), and 22:30 in Adelaide, Australia. To define Adelaide’s location to CICSPlex SM, the time zone is specified as time zone J, and the time zone adjustment is specified as 30 (to indicate that the time in Adelaide has 30 minutes added to the time in the adjacent time zone to the west).
Daylight Savings
Some locations around the world modify their time offset from GMT twice a year. Usually, the first change occurs in March or April, when local standard time (LST) is moved ahead by one hour, creating local daylight savings time (LDST). For locations in time zones Z through M, LDST is one hour farther ahead of GMT. For locations in time zones N through Y, LDST is one hour closer to GMT. In October or November, locations that use LDST usually change back to LST. Time in these locations then reverts to the standard difference from GMT.

For operation of CICSPlex SM, sites in locations that make use of LDST must modify the appropriate CICSPlex SM definition twice a year. This means indicating YES to daylight savings when LDST is in effect, and NO when LST is in effect. When the daylight savings indicator is NO, CICSPlex SM considers an entity in that time zone to be the normal number of hours from GMT. When the daylight savings indicator is YES, CICSPlex SM considers that entity to be one hour further ahead of GMT (than during standard time) for time zones Z through M, and one hour closer to GMT for time zones N through Y.

Note:
After changing the system time to adjust for LDST, you need to use the PERFORM RESETTIME command in the CMAS.

Attribute usage

You make use of the three attributes that facilitate timing services when you specify the following definitions:

CMAS
In order to ensure consistent timing services, CICSPlex SM requires that the attribute settings within a CMAS accurately reflect the time in effect for the location in which that CMAS executes.

There are three uses for these attributes in a CMAS:

CICSplex
Because a CICSplex may encompass many different time zones, and in order to ensure consistency within the CICSplex, it is required that a single set of attributes be chosen to represent the CICSplex. It is not necessary that the attributes chosen match the attributes of the maintenance point CMAS of the CICSplex, or any other CMAS.

There is one use for the time zone attributes in a CICSplex:

CICS system
Unlike the attribute requirements for a CMAS, the time zone attributes for a CICS system can be set to reflect a location different from that where the CICS system actually executes. For example, if the system executes in one time zone, but is primarily used by operators in another time zone, you may prefer to set the attributes to match the time zone of the operators, instead of matching the time zone where the system executes. CICSPlex SM supports either actual or logical attributes for CICS systems.

There are three uses for these attributes in a CICS system:

Period definition
Period definitions are used by CICSPlex SM to schedule timed events. A period definition is defined as a starting time, an ending time, and time zone attributes. Period definitions use only two of the time zone attributes: the time zone and the time zone adjustment.

There are three uses of period definitions:

For a period definition, there are two differences from other uses of the time zone attributes:

When a period definition is for time zone A, all events controlled by that period definition become active at the same clock time, based upon the start time specified in the period definition, and the time zone, time zone adjustment, and daylight saving indicator within the entity (CMAS or CICS system). Similarly, events become inactive at the same clock time, based upon the end time specified in the period definition, and the time zone, time zone adjustment, and daylight saving indicator within the entity (CMAS or CICS system).

When a period definition is for a time zone other than time zone A, all events controlled by that period definition become active at exactly the same real time, regardless of the time zone in which the events are occurring. The activation time is based upon the period definition’s start time, time zone, and time zone adjustment. Similarly, events controlled by that period definition become inactive at the same real time, based upon the period definition’s ending time, time zone, and time zone adjustment. For both activation and deactivation, the time zone specified refers to the standard time for that time zone (LST), regardless of whether daylight saving time is in effect.

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