Given an invocation context block and SSE (Streaming SIMD
    Extensions) register index such that 0 <= index < 32, copy the
    register value to zmm_copy. For example, an index value of 4
    fetches the value, which represents the contents of zmm4.
    LIB$X86_GET_ZMM returns failure status if there is no
    corresponding XSAVE save area in the invo_context or if the
    index represents a register or register set not saved in the
    XSAVE save area.

    Format
      LIB$X86_GET_YMM (invo_context, index, zmm_copy)