invo_context

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

    Address of a valid invocation context block. The given
    invocation context block is updated to represent the context of
    the previous (calling) frame.

    The LIBICB$V_BOTTOM_OF_STACK flag of the invocation context
    block is set if the target frame represents the end of the
    invocation call chain or if stack corruption is detected.