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

  Sends the signal SIGALRM to the invoking process after the number
  of seconds indicated by its argument has elapsed.  This function is
  nonreentrant.

  Syntax:

       #include <unistd.h>

       unsigned int alarm(unsigned int seconds);  (POSIX-1)

       int alarm(unsigned int seconds);  (Compatibility)