jpa/subsystem/src/main/java/org/jboss/as/jpa/container/SFSBCallStack.java
public static void pushCall(Map<String, ExtendedEntityManager> entityManagers) {
        currentSFSBCallStack().add(entityManagers);

        if (entityManagers != null) {
            /**
             * JPA 2.0 spec section 7.9.1 Container Responsibilities:
             * "When a business method of the stateful session bean is invoked,
             *  if the stateful session bean uses container managed transaction demarcation,
             *  and the entity manager is not already associated with the current JTA transaction,
             *  the container associates the entity manager with the current JTA transaction and
             *  calls EntityManager.joinTransaction.
             *  "
             */
            for(ExtendedEntityManager extendedEntityManager: entityManagers.values()) {
                extendedEntityManager.internalAssociateWithJtaTx();
            }
        }

    }
public static void pushCall(Map<String, ExtendedEntityManager> entityManagers) {
        currentSFSBCallStack().add(entityManagers);

        if (entityManagers != null) {
            /**
             * JPA 2.0 spec section 7.9.1 Container Responsibilities:
             * "When a business method of the stateful session bean is invoked,
             *  if the stateful session bean uses container managed transaction demarcation,
             *  and the entity manager is not already associated with the current JTA transaction,
             *  the container associates the entity manager with the current JTA transaction and
             *  calls EntityManager.joinTransaction.
             *  "
             */
            for(ExtendedEntityManager extendedEntityManager: entityManagers.values()) {
                extendedEntityManager.internalAssociateWithJtaTx();
            }
        }

    }
Push the passed SFSB context handle onto the invocation call stack

@param entityManagers the entity manager map