You may also want to change the enterprise bean's transaction attribute (in the deployment descriptor) from 'Supports' to 'Mandatory'. If you do this, CICS allows the remote method of the bean to be invoked only if an existing OTS transaction context is passed from the client's environment on the call.
If, on the other hand, you leave the enterprise bean's transaction attribute set to 'Supports', CICS binds the method invocation to the client's transaction context if such a context exists; otherwise the method runs in an atomic transaction and does not propagate a new transaction context when calling other beans.
If you set the transaction attribute to 'Mandatory' but don't update the servlet to use client-demarcated transactions, when you run the sample CICS throws a javax.transaction.TransactionRequiredException. This is because no transaction context has been sent.