How to resolve - JBAS014516: Failed to acquire a permit within 5 MINUTES

I am currently facing 'JBAS014516: Failed to acquire a permit within 5 MINUTES' issue with my EJB-JBOSS configuration.Below is my configuration -

<subsystem xmlns="urn:jboss:domain:ejb3:1.4">
        <session-bean>
            <stateless>
                <bean-instance-pool-ref pool-name="slsb-strict-max-pool"/>
            </stateless>
            <stateful default-access-timeout="5000" cache-ref="simple"/>
            <singleton default-access-timeout="5000"/>
        </session-bean>
        <mdb>
            <resource-adapter-ref resource-adapter-name="hornetq-ra"/>
            <bean-instance-pool-ref pool-name="mdb-strict-max-pool"/>
        </mdb>
        <pools>
            <bean-instance-pools>
                <strict-max-pool name="slsb-strict-max-pool" max-pool-size="20" instance-acquisition-timeout="5" instance-acquisition-timeout-unit="MINUTES"/>
                <strict-max-pool name="mdb-strict-max-pool" max-pool-size="20" instance-acquisition-timeout="5" instance-acquisition-timeout-unit="MINUTES"/>
            </bean-instance-pools>
        </pools>
        <caches>
            <cache name="simple" aliases="NoPassivationCache"/>
            <cache name="passivating" passivation-store-ref="file" aliases="SimpleStatefulCache"/>
            <cache name="clustered" passivation-store-ref="abc" aliases="StatefulTreeCache"/>
        </caches>

        <async thread-pool-name="default"/>
        <timer-service thread-pool-name="default">
            <data-store path="timer-service-data" relative-to="jboss.server.data.dir"/>
        </timer-service>
        <remote connector-ref="remoting-connector" thread-pool-name="default"/>
        <thread-pools>
            <thread-pool name="default">
                <max-threads count="10"/>
                <keepalive-time time="100" unit="milliseconds"/>
            </thread-pool>
        </thread-pools>
        <iiop enable-by-default="false" use-qualified-name="false"/>
        <default-security-domain value="other"/>
        <default-missing-method-permissions-deny-access value="true"/>
    </subsystem>

To resolve this should i increase the 'strict-max-pool' to a higher value or increase thread pool size.