I had this same problem with MQ 5.3.1 on OS/390. The resolution was to use the RCVTIME parameter in the chinit for the queue manager (sending queue manager in this case).
The queue that was getting put to was a remote queue. There was no indication of channel trouble to the remote system, so I'm sure that the problem was not wi ...
We have had a problem recently where applications on Solaris have reported a 2056 when trying to put to a queue. I have read through many posts on this subject and have a general undertanding of the ...