As a general rule each CA Datacom release adds more internal system tasks for product enhancements. However, unless the new CA Datacom release documents it there is no need to increase CA Datacom FXX TASKS value. The recommendation has been that the number of FXX TASKS should always have a pad so that resizing would not be an issue when upgrading to a new release. A pad of 100 extra FXX tasks would be considered good for many releases.
The CA Database and System Administration Guide chapter "Chapter 18: Creating and Maintaining the Force Area (FXX)" explains the FXX.