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

  deallocates the address space allocated by the Compaq C RTL for the
  handle.

  There is no way on OpenVMS systems to "unload" a shareable image
  that was dynamically loaded by the LIB$FIND_IMAGE_SYMBOL routine,
  which is the routine called by the dlsym function.  In other words,
  there is no way on OpenVMS systems to release the address space
  occupied by the shareable image brought into memory by dlsym.

  Syntax:

       #include <stdio.h>

       void dlclose(void *handle);