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

  Changes the size of the area pointed to by the first argument to
  the number of bytes given by the second argument.  This function is
  AST-reentrant.

  Syntax:

       #include <stdlib.h>

       void *realloc(void *pointer, size_t size);