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

  Sets a specified number of bytes in a given object to a given
  value.

  memset copies value (converted to an unsigned char) into each of
  the first size characters of the object pointed to by s.

  Syntax:

       #include <string.h>

       void *memset (void *s, int value, size_t size);