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

    OpenVMS usage:boolean
    type:         boolean
    access:       write only
    mechanism:    by value

    Truth value that indicates whether an AST is currently in
    progress (value = 1) or not (value = 0).