WSAIoctl问题

Question

int WSAIoctl (
  SOCKET s,                                               
  DWORD dwIoControlCode,                                  
  LPVOID lpvInBuffer,                                     
  DWORD cbInBuffer,                                       
  LPVOID lpvOUTBuffer,                                    
  DWORD cbOUTBuffer,                                      
  LPDWORD lpcbBytesReturned,                              
  LPWSAOVERLAPPED lpOverlapped,                           
  LPWSAOVERLAPPED_COMPLETION_ROUTINE lpCompletionROUTINE  
);
参数lpvInBuffer, lpvOUTBuffer, lpcbBytesReturned有什么用？应如何设置？