This routine should be called at the conclusion of call tracing
    operations to free the memory used to process unwind
    descriptors. The call tracing routines are
    LIB$X86_GET_INVO_CONTEXT, LIB$X86_GET_PREV_INVO_CONTEXT, and
    LIB$X86_GET_CURR_INVO_CONTEXT.
    To provide efficient call tracing, some unwind information is
    tracked in heap storage from one call to the next. This heap
    storage should be freed before you release or reuse the
    invocation context block.
    Calling this routine is necessary if the
    LIBICB$V_UO_FLAG_CACHE_UNWIND flag is set in the
    LIBICB$Q_UO_FLAGS field of the invocation context block. If
    this flag is not set, unwind information is released and
    recreated at each call, and calling this routine is not
    required.

    Format
      LIB$X86_PREV_INVO_END (invo_context)

1  –  Returns

 status

    A value of 1 indicates success. A value of 0 indicates failure.

2  –  Argument

 invo_context

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

    Address of a valid invocation context block previously used for
    call tracing.