Compatibility mode (–compat[=4])
If –library is not specified, -library=libC is assumed.
The libC library is always included unless it is specifically excluded using -library=no%libC.
Standard mode (the default mode)
The libCstd library is always included unless it is specifically excluded using -library=%none or -library=no%Cstd or -library=stlport4.
The libCrun library always is included.
Regardless of standard or compat mode, the libm and libc libraries are always included, even if you specify -library=%none.