See this KB entry

Setting tomcat.util.buf.StringCache.byte.enabled=true seems to enable caching of a class called ByteChunk. This in turns leads to a growing cache of memory.

this is documented here

http://tomcat.apache.org/tomcat-6.0-doc/config/systemprops.html

Although this is a 6.0 document (and I cant find it in the 5.5 documentation) a search of the 5.5 code shows that it is used in 5.5

What can we do?

We should probably look for this being set in the JIRA startup and then log a warning. It may be possible to turn this off dynnamically but it appears that the system property is static referenced and hence we may not get a chance.

The Tomcat 5.5 class is called org.apache.tomcat.util.buf.StringCache