z/OS Installation - Time Zone Environment Variable

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Jan 31, 2024

Time Zone Environment Variable

Universal Agent components execute in a z/OS UNIX environment, also known as a POSIX(ON) Language Environment.

The z/OS UNIX environment assumes that the z/OS system time is GMT or UTC format. It then uses the TZ environment variable value to determine the adjustments required for local time.

The TZ environment variable is an IBM Language Environment (LE) environment variable with a value set to the appropriate time zone and offset information so that time values are properly processed. TZ allows you to set the standard and daylight savings (or summer time) time zones and the offset from the local time zone to the UTC time.

LE environment variables, such as TZ, are set with the LE option ENVAR using the JCL step PARM keyword. For example, the following statement sets the standard time zone to Eastern Standard Time (EST) with an offset of 5 hours and the daylight saving time zone to Eastern Daylight Saving Time (EDT).


//PS1      EXEC PGM=UCMD,PARM='ENVAR(TZ=EST5EDT)/&UPARM'

Note

The forward slash ( / ) character separates the LE runtime parameters from the program parameters.

North American Values

TZ environment variables values for North America are listed below.

  • EST5EDT: Eastern Standard Time, Eastern Daylight Time
  • CST6CDT: Central Standard Time, Central Daylight Time
  • MST7MDT: Mountain Standard Time, Mountain Daylight Time
  • PST8PDT: Pacific Standard Time, Pacific Daylight Time
  • AKST9AKDT: Alaska Standard Time, Alaska Daylight Time

European Values

TZ environment variables values for Europe are listed below.

  • GMT0BST: Greenwich Mean Time, British Summer Time
  • WET0WEST: Western Europe Time, Western Europe Summer Time
  • CET-1CEST: Central Europe Time, Central Europe Summer Time
  • EET-2EEST: Eastern Europe Time, Eastern Europe Summer Time
     

Other common time zone abbreviations may be used. IBM does not document all possible values.

Customizing the Start and End of Daylight Saving Time

An optional rule that specifies when daylight saving time begins and ends can be appended to the TZ environment variable value.

The format of this rule is [,startdate[/time],enddate[/time]].

You must specify startdate and enddate in one of the following formats:

Jn

The Julian day, where n is in the range 1 to 365, inclusive. This format cannot handle leap days. J59 is always February 28 and J60 is always March 1.

n

The Julian day, where n is in the range 0 to 365, inclusive. This format does support leap days:

  • In non-leap years, day 59 is March 1 and day 364 is December 31.
  • In leap years, day 59 is February 29 and December 31 is day 365.

Mm.n.d

Where:

  • m is the month in the range 1 to 2, inclusive.
  • n is the week of the month in the range 1 to 5, inclusive.
  • d is the day of the week in the range 0 to 6, inclusive.

Use week 5 to specify the last occurrence of a particular day within the specified month. Week 1 always refers to the first occurrence of a given day within the specified month. For example, M3.5.0 is the last Sunday in March and M11.1.0 is the first Sunday in November.

time has the format HH[:MM[:SS]]. If time is omitted from the rule, the default time is 02:00:00.

Additional Information

For more information on the TZ environment variable, see the z/OS Unix System Services Command Reference manual.