After applying the update, the TN3270 server no longer sends requests to the host when the host is expecting a response for that particular session. In addition, it no longer queues requests from clients when it is expecting a response from the client. The issue described here is extremely hard to reproduce because the timing window that allows this to occur is very small. TN3270 Server sends this to the client, which unlocks the keyboard. At this point, the client is able to send data.
Host sends a BID to initiate a new Bracket on the session.
Host sends an RU that contains data. The TN3270 server sends this data to the client indicating the a response is required to acknowledge the receipt of the data. The client presses a key to send data to the host. The timing has to be such that the last two steps occur at approximately the same time for the problem to occur. Once the TN3270 client receives the data from the host, the keyboard locks until all of the data is received and the client receives direction to send.