We are moving our software towards multithreading (SunOS 5.5.1). One of the many concerns is the MT-unsafety of tzset() function. It is said to be MT-unsafe in man pages. It is partly due to the keeping references to TZ in the environment variable, I guess. Our software needs to deal with more than one timezone in one process. The only way I know to implement it is to change the value of environment variable TZ and call tzset() every time I want to switch to a new timezone. External variables tzname and others also makes it problematic to maintain access to them: other vendors' software we are using might use their own policy of access. How is it possible to manage current zone information in MT-safe fashion? I would appreciate any help. Valery