There are no such tuning options for rollback segments. This is probably a problem with failing to retain undo blocks in cache for long enough after they have been modified.

Even I have over 12 rollback segments and the max concurrent transaction is 4, I still get some undo header and undo block waits from V$WAITSTAT. Is it possible to increase the FREELIST or FREELIST GROUP for those rollback segments to alleviate this problem just like what we do for normal tables or data segments?