If you are finding a websocket library which completely implement Websocket protocol RFC 6455).
I would like to introduce WebsocketSharp. 
Although there is no size implementation for websocket, the limitations of websocket implementations are different. The original websocketsharp’s text buffer(initial frame size) is 1016 characters. If you want to increase the suze, please download the source codes and modify FragmentLength in Websocket.cs. 
- IETF, “RFC 6455:Websocket protocol”, URL: https://www.rfc-editor.org/rfc/rfc6455
- Websocket-Sharp, URL:http://sta.github.io/websocket-sharp/
- “How to disable force Frame continuations in websocket sharp?” URL: https://stackoverflow.com/questions/27414791/how-to-disable-forced-continutation-frames-using-websocket-sharp-in-c-sharp
- “Websocketsharp.cs”, URL: https://github.com/sta/websocket-sharp/blob/master/websocket-sharp/WebSocket.cs