All connection usage occurs within the scope of either a global transaction or a local transaction containment (LTC) boundary. Each transaction type places different requirements on connections and impacts connection settings differently.
You can share connections within a global transaction scope (assuming other sharing rules are met). You can also share connections within a shareable LTC. You can serially reuse connections within an LTC scope. A get/use/close connection pattern followed by another instance of get/use/close (to the same data source or connection factory) enables you to reuse the same connection. See the topic, Unshareable and shareable connections for more details.
One-phase commit resources are such that work being done on a one phase connection cannot mix with other connections and ensure that the work done on all of the connections completes or fails atomically. The product does not allow more than one one-phase commit connection in a global transaction. Futhermore, it does not allow a one-phase commit connection in a global transaction with one or more two-phase commit connections. You can coordinate only multiple two-phase commit connections within a global transaction.
WebSphere Application Server provides last participant support, which enables a single one-phase commit resource to participate in a global transaction with one or more two-phase commit resources.
WTRN0063E: An illegal attempt to enlist a one phase capable resource with existing two phase capable resources has occurred.