DB2 connection time out error

Hi to all,
I have wrote a jsp-servlet program(using struts) which connects to DB2 via JDBC.

I am using Tomcat5.5.
JDBC driver as400thinjdbc.jar .
DB connection paramaters are

<data-sources>
<data-source id="DB2" type="org.apache.tomcat.dbcp.dbcp.BasicDataSource">
<set-property property="username" value="XXXX"/>
<set-property property="maxActive" value="10"/>
<set-property property="password" value="XXXX"/>
<set-property property="url" value="jdbc:as400://XX.XX.XX.XX/MYLIB"/>
<set-property property="defaultAutoCommit" value="false"/>
<set-property property="maxWait" value="5000"/>
<set-property property="driverClassName" value="com.ibm.as400.access.AS400JDBCDriver"/>
</data-source>
</data-sources>

The program is running fine and giving me all the expected values from DB2 BUT after 1hr or 2 or 3hrs of discontinuity from my web application,when I try to connect DB2 it takes 10-15 minutes.
Sometimes it gives "Connection time out error" stating in my log file.

I googled the internet but couldn't found any satisfied solution.

I changed my driver to jt400.jar but no luck.

Can you experts please point out the mistake I am doing.

Thanks in advance.