Arma has several of its own memory allocation settings it tries to use instead of what your OS already has in place (which is stable). If you continue with crashing with memory issues, ensure that Arma is not loading one of its malloc settings. You can do this by deleting the malloc .dlls in its DLL folder in your main Arma 3 file path, or, using the Arma launcher, you can select it to use system (your OS) malloc.