CCS compiler support for #pragma pack(n)

I have some structures shared between an Stellaris project and a Microsoft's Visual Studio project

When I try to build my Stellaris project with CCS, it does not recognize the #pragma pack(4) statement. 

When I search on the WWW, I read that GCC compilers are supossed to support the aforementioned pragma.

Can anyone help me with this question ?

Thank you.