Serializable exception in spring mvc application

I am developing webapplication using Spring MVC and Tomcat. Sometimes I am getting java.io.NotSerializableException exception.

Caused by:

java.io.NotSerializableException:
 org.springframework.jdbc.datasource.DriverManagerDataSource

Here is my datasource in spring config.xml

 <bean id="dataSource"  
    class="org.springframework.jdbc.datasource.DriverManagerDataSource" >  
    <property name="driverClassName" value="com.ibm.db2.jcc.DB2Driver" />  
    <property name="url" value="jdbc:db2:DB212cc" />  
    <property name="username" value="#XYZ" />  
    <property name="password" value="1234" />  
</bean>

Can any one suggest me where and how to serialize this datasource.

I am using spring-jdbc-4.0.0.M2.jar