invo_handle

    OpenVMS usage: invo_handle
    type:          quadword
    access:        read
    mechanism:     by reference

    Address of the location that contains the handle for the
    desired invocation.

 invo_context

    OpenVMS usage: invo_context_blk
    type:          structure
    access:        modify
    mechanism:     by reference

    Address of an invocation context block into which the procedure
    context of the frame specified by invo_handle will be written.

    The invocation context block must be properly initialized. For
    information, see the VSI Calling Standard guide.

    If the invocation handle that was passed does not represent any
    procedure context in the active call stack, the new contents of
    the context block is unpredictable.