The point is that I don't know how to provide a self-contained query. 

The only strategy I could propose, to provide a self-contained query isolating the memory management problem, is really too time-consuming : I can imagine a binary-chop search, comparing the memory management of the two BaseX beta versions, over a very complex algorithm, to isolate the problem. This is probably a week work, I can't spend such a time.

Do you have a better strategy to find the problem ?