How many database partitions can a DPF system have (it is 999 partitions)? How many levels deep can an XML document stored in DB2 be (125 levels)? What is the maximum size of an SQL statement I can code (2097152 bytes)?
If you have questions like that around DB2, then the page SQL and XML limits in the DB2 Information Center is the right one for you. And if you have lots of users, rest assured, the maximum number of concurrent users for a system is 64000.