Rational Build Forge is made up of several components. Each component keeps its own logs.
Under some conditions a component will write a large amount of data. This can be true of the catalina log files produced by Tomcat. By design the Tomcat out log is not rotated. Under unusual conditions the out log may grow much larger than desired.
There are two ways to work around this issue:
start >> catalina.out 2>&1 & --replaced with
start |cronolog /tomcat/logs/%Y-%M-%D.catalina.out >> /dev/null 2>&1 &