| Syntax: | Default: |
| /M[p|s|c|t] | /Mp |
Use /M to set the default calling convention, as follows:
| Option | Calling Convention |
| /Ms | _System |
| /Mc | __cdecl |
| /Mt | __stdcall |
| /Mp | _Optlink |
The default is the _Optlink calling convention (/Mp).
You must include the header files for libraries that use a different calling convention from the one you specify. The libraries use the following calling conventions:
| IBM C and C++ Compilers | Functions use the _Optlink calling convention. Include the IBM C and C++ Compilers library header files to call IBM C and C++ Compilers functions when you set /Ms, /Mc, or /Mt. |
| Toolkit libraries | APIs use the __stdcall calling
convention.
|
If you do not include the header files, then your code will attempt to call functions with the calling convention you set, rather than with the calling convention the function requires.