cb (USHORT)
Binary integer with the size of the physical device driver receive/transmit queue. Applications should be independent of the receive/transmit queue size (fixed or not fixed). The information in this field allows the application to get the size of the receive/transmit queue, but is subject to change. The current size of the receive queue is approximately 1KB.
Using this information, the application should avoid device driver receive queue overruns by using an application-to-application block protocol with the system communicating with the application.