How to BUILD_SHARED_LIBS

[IOTeule]

What is the correct approach to build with shared libs ?
I changed Dockerfile section to
[...]
RUN cmake /src/Sample-Server/.github/
-DCMAKE_BUILD_TYPE=${BUILD_TYPE}
-DBUILD_SHARED_LIBS:BOOL=ON
-DCMAKE_INSTALL_PREFIX:PATH=/install /build &&
cmake --build .
[...]
But during build CMake says manually BUILD_SHARED_LIBS is not used.