Facing concurrency issue when trying to call Web Services with CXF and WSS4J interceptors

Issue

• Exposed an SLSB (Stateless EJB) as an JAX-WS JBOSS managed Web Service, and are trying to use CXF interceptors and WS4J interceptors to authenticate the request.
• Below are the configuration settings that have been applied:
  • jbossws-cxf.xml

<jaxws:endpoint id="SecuredEJBEndpoint"
              address="/somecontext/secure/PostEndpoint" implementor="EJBBean">
              <jaxws:invoker>
                     <bean class='org.jboss.wsf.stack.cxf.JBossWSInvoker' ></bean>
              </jaxws:invoker>
              <jaxws:inInterceptors>
                     <ref bean="httpHeaderUsernameTokenInInterceptor" ></ref>
                     <ref bean="wss4jIn"></ref>
              </jaxws:inInterceptors>
              <jaxws:properties>
                     <entry key="ws-security.validate.token" value="false"></entry>
                     <entry key="ws-security.ut.no-callbacks" value="true"></entry>
                     <entry key="ws-security.ut.validator" value-ref="ldapUsernameTokenValidator"></entry>
              </jaxws:properties>
       </jaxws:endpoint>

• EJB configuration in jboss-ejb3.xml file:

<session>
                     <ejb-name>SecuredEJBEndpoint</ejb-name>
                     <business-remote>PostEndpoint</business-remote>
                     <ejb-class>EJBBean</ejb-class>
                     <session-type>Stateless</session-type>
                     <transaction-type>Bean</transaction-type>
       </session>

• jboss-webservices.xml:

       <port-component>
              <ejb-name>SomeEndpoint</ejb-name>
              <port-component-name>PostEndpoint</port-component-name>
              <port-component-uri>/secure/PostEndpoint</port-component-uri>
       </port-component>

• EJB is not getting pooled, we are seeing always single instance of EJB. This causing concurrency issues. Is there any configuration which will prevent this issue?