TMS320F28388D: How to get C++ .cpp to compile for TMS320F28388D on Code Composer

I cannot get C++ to compile.

I have this:

#include <string>
#include <string.h>
#include <iostream>


string tst1()
{
    string strtst = "This is a test.";

    return strtst;
}

and when I try to build the project I get this error:

error #20: identifier "string" is undefined

In project properties it shows

"C++ Dialect   Compile program in C++03 mode (--c++03)

How can I get Code Composer to Compile and Link C++ program?

Thanks.