win32s brings codepage to/from widechar APIs and codepage table files (P_*.NLS), and a setting "AnsiCP=" in [NLS] section in win32s.ini.
16bit IE brings its own MSNLS.DLL for handling different codepages to ACP(Active Codepage) in Win3.1x.
and win9x also works mainly in ANSI codepage with some kernel side unicode support.