Configuring the XML Libraries
Stxx requires a later version of a JAXP 1.2-compatible XML library and if Xalan/Xerces are used, a later version of both libraries are strongly recommended. The use of the XML libraries varies depending on what version of Java is being used.
Since Sun's Java 1.4 comes with an older version of Xalan, the XML libraries in the directory libs/core/endorsed need to be copied to $JAVA_HOME/lib/endorsed. For more information, see the Xalan FAQ.
Java 1.3.1 or earlier
Since older versions of Java don't contain any XML libraries, simply copying the jars in libs/core/endorsed to /WEB-INF/lib of your web application will suffice.
by Don Brown