Here is an update on this issue for anyone using the JTOpen driver to connect to DB2.
The JTOpen driver can be downloaded from the JTOpen page on sourceforge.net as a zip file. The 'lib' folder contains a file named jt400.jar. However, do not use this file. Instead, navigate to the 'lib/java8' folder and use the jt400.jar file located in that folder as this file is compiled for use with Java 8 - which is used by the Dataverse application.
Additional comments:
The DbUrl property value should be of the form:
jdbc:as400://<host>:<port>/<dbname>
Driver options can be included in the DbUrl connection string as shown in the original post. Alternatively, options can be specified in the node's DbOptions property as a comma-separated list of key=value pairs.
The prompt=false option will prevent the driver attempting to open a pop-up sign-in window when the user credentials are not specified on the node. On certain Linux systems, if prompt=false is not set the credentials problem can manifest itself as an error relating to X11.