VMS Help CC, Run-time functions, setlocale  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Selects the appropriate portion of the program's locale as
  specified by the category and locale arguments.  This function can
  be used to change or query one category or the program's entire
  current locale.

  Syntax:

       #include <locale.h>

       char *setlocale(int category, const char *locale);