VMS Help RTL Routines, LIB$, LIB$SFREE1_DD, Argument  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 descriptor-address

    OpenVMS usage:descriptor
    type:         quadword (unsigned)
    access:       modify
    mechanism:    by reference

    Dynamic descriptor specifying the area to be deallocated. The
    descriptor-address argument is the address of an unsigned
    quadword that is this descriptor. The descriptor is assumed to
    be dynamic and its class field is not checked.