ORA-02049 and ORA-02063 Errors
It's not necessarily the number of transactions, but the timeout. The parameter distrubuted_lock_timeout is set to 60 seconds by default. The purpose of this parameter is to avoid having distributed transactions in a long running wait status while something else is performing work on that row; the transaction will wait 60 seconds, then Oracle kills it. 

You can modify this parameter (requires an instance restart) to whatever you want (in seconds).