For V5R4, general information on this can be found in the Information Center <a href=”http://publib.boulder.ibm.com/infocenter/iseries/v5r4/index.jsp?topic=/rzamp/rzampoverview.htm”>Maximum capacities</a> topic.
A couple related elements from that topic:
Maximum number of records contained in a file member: 4 294 967 294 records
Maximum number of members in a physical or logical file 32 767
Maximum number of data partitions in a single partitioned table 256
Now, how you choose to handle a RRN() value is up for a lot of debate.