/sys$common/syshlp/helplib.hlb CC, Run-time functions, clock  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Determines the amount of CPU time (in 10-millisecond units) used
  since the beginning of program execution.  The time reported is the
  sum of the user and system times of the calling process and any
  terminated child processes for which the calling process has
  executed wait or system.  This function is nonreentrant.

  Syntax:

       #include <time.h>

       clock_t clock(void);