The dlclose function 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
    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.