FreeStreams is a Boolean property used to indicate if the stream instances in SendStream and ReceiveStream are owned by the IOHandler. 

FreeStreams is used in Close. When FreeStreams is True, stream instances allocated to the ReceiveStream and SendStream properties are freed in the destructor. 

The default value for FreeStreams is True, as assigned in the Create method. 

Change the value for FreeStreams to False if streams instances are handled in the application. 

Use OnGetStream to create stream instances for the IOHandler.

TIdIOHandlerStream.Close 

TIdIOHandlerStream.Create 

TIdIOHandlerStream.Destroy 

TIdIOHandlerStream.ReceiveStream 

TIdIOHandlerStream.SendStream 

TIdIOHandlerStream.OnGetStream