What is needed here is to set the custom property nonTransactionalDataSource=true on the XA datasource for the IM task persistence database.
Within the Websphere Application Server, the use of the <non-jta-data-source> element requires a special configuration for a non-transactional data source.
Data sources that are configured for the application server will not function as a <non-jta-data-source>, because all data sources that are configured by the application server are automatically enlisted with the current transactional context. To prevent this automatic enlistment, add an additional data source custom property nonTransactionalDataSource=true, following these steps:
1. Select Resources > JDBC > Data sources
2. Select the name of the data source that you want to configure. In this case, task persistence.
3. Select Websphere Application Server data source properties from the Additional Properties heading.
4. Select Non-transactional data source.
5. Click OK.
6. Restart Websphere Application Server.