By now, every man and his dog is probably familiar with the various bugs that have surfaced from 8.1.5.x to 8.1.6.x when activating the two parameters
Various posts on Metalink and other forums have suggested an alternative,
using the hidden parameter
Much of the information on Metalink is non-committal about the effectiveness of the parameter (see Note 68955.1), so if you do want to use it, make sure you do some monitoring to see if you're getting any joy.
Obviously before you even consider any of this, first check to see if your version counts are growing abnormally. The following Steve Adams script can be used to assist in this area
select to_char(min(v)) || decode( max(v) - min(v), 0, null, ' to ' || to_char(max(v)) ) version_count, count(*) cursors from ( select count(*) v from sys.x_$kglcursor where inst_id = userenv('Instance') and kglhdadr != kglhdpar group by kglhdpar, kglnahsh ) group by trunc(round(log(2, v), 37)) /