/sys$common/syshlp/helplib.hlb RTL Routines, STR$, STR$FREE1_DX, Argument  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 string-descriptor

    OpenVMS usage:char_string
    type:         character string
    access:       modify
    mechanism:    by descriptor

    Dynamic string descriptor of the dynamic string that STR$FREE1_
    DX deallocates. The string-descriptor argument is the address
    of a descriptor pointing to the string to be deallocated. The
    descriptor's CLASS field is checked.