The standard stdio functions are shadowed by the fcgi_stdio functions in some but not all parts of the ZOO kernel. As tested on Windows, running a service (e.g. longProcess) with storeExecuteResponse=true and status=true may fail because the ExecuteResponse? is not written to the temporary <service>_final_<pid>.xml file via redirection of stdout. Putting #include "cgic.h" in service_internal.h resolved this problem.

Update: In some services it may be necessary to use standard stdio. For example, Visual C++ has a superset of wide character print functions, not redefined in fcgi_stdio.h, that take FILE* as a parameter (not FCGI_FILE*). This can easily be resolved by putting #define NO_FCGI_DEFINES at the beginning of the service source code.