Time functions

If you are migrating from IBM® C/370™ (Version 1 or Version 2) or AD/Cycle C/370 (Version 1 Release 1 or Version 1 Release 2), you should be aware of the following change in time functions.

• The ctime(), localtime(), and mktime() functions will return Coordinated Universal Time (UTC) time unless customized locale information is available. When you customize the locale, time functions preserve the time and date and correctly adjust for daylight time on a given date. See z/OS XL C/C++ Programming Guide for more information about environment variables and customizing locale information.
• In POSIX and non-POSIX applications, you can use the TZ environment variable to supply the necessary time zone information for your location. Previously, for non-POSIX applications, you could supply customized locale information only by setting time zone and daylight information in the LC_TOD locale category.