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

  Suspends the execution of the current process for at least the
  number of seconds indicated by its argument.

  Syntax:

       #include <unistd.h>

       _DECC_V4_SOURCE defined:

       unsigned int sleep(unsigned seconds);

       _DECC_V4_SOURCE not defined:

       int sleep(unsigned seconds);