如何使tcpclient在线程中停止?

我有一个线程按照tcpconnect方法运行。我希望在任何给定时间通过将program.prepareExit设置为true来停止它。但是,我的程序仍停留在:
Int32 bytes = stream.Read(data, 0, data.Length); 对程序没有真正的反应。PrepareExit设置为true。当我这么说的时候,我怎么能总是放弃呢?

    public static readonly Thread MyThreadTcpClient = new Thread(ThreadTcpClient);
    private static void ThreadTcpClient() {
        Connections.tcpConnect(ClientTcpIp, ClientTcpPort);
    }

         public static void Main() {

             MyThreadTcpClient.Start();
             .... some code....
             Program.PrepareExit = true;
        }

    public static bool tcpConnect(string varClientIp, int varClientPort) {
        var client = new TcpClient();
        try {
            client = new TcpClient(varClientIp, varClientPort) {NoDelay = true};
            NetworkStream stream = client.GetStream();
            var data = new Byte[256];
            while (!Program.PrepareExit) {
                Int32 bytes = stream.Read(data, 0, data.Length);
                string varReadData = Encoding.ASCII.GetString(data, 0, bytes);
                if (varReadData != "" && varReadData != "echo") {
                    VerificationQueue.EnqueueRelease(varReadData);
                }
            }
        } catch (ArgumentNullException e) {
            MessageBox.Show(e.ToString(), "ArgumentNullException");
            tcpConnect(varClientIp, varClientPort);
        } catch (SocketException e) {
            MessageBox.Show(e.ToString(), "SocketException");
            tcpConnect(varClientIp, varClientPort);
        } catch (IOException e) {
            if (e.ToString() != "Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.") {
            }
            MessageBox.Show(e.ToString());
            tcpConnect(varClientIp, varClientPort);
        } finally {
            client.Close();
        }
        return false;
    }