b5eeb599__the_C___Command_Line_Compiler__Details
[Option] -tWM [Description] Generate a multi-threaded target [Details] 
Creates a multi-threaded .EXE or .DLL. This option is not needed if you include a module definition file (.DEF file) in your compile and link commands which specify the type of 32-bit application you intend to build.
BCC32, the C++ Command-Line Compiler
Details