There is another concept besides Pass By Value and Pass By Reference, it is the "Pass By Value with Reference".
This comes into picture for the Shared Business Objects.
Please consider the below scenario.
For example, a shared object is passed by value with reference from a process to two different services. The process and services each contain a separate copy of the business object. When the first service completes, the shared object values are automatically persisted to the data store. When the second service starts, the shared object values are automatically loaded from the data store. So even though the process and the two services reference separate objects, the values of these objects are updated by the data store and the services operate on current data.