Transaction rollback and set lock mode to wait 3

The core bank system of a customer use IDS9.30FC3WC, One time I use onstat -p to monitor the database, And I find that every 11 transactions have one transcation rollback, It's very high,So online exhaust many resource. The customer want to improve the successful transaction numbers. And I use onstat -g sql find that mostly the application use 'set lock mode to wait 3'. Three seconds is a short value. So I feel that's the reason for too many transaction rollback. Another question is how to find the table being rollbacked.