TABLESIZE 
The system table SYSINFO.TABLESIZE contains size information about tables.
Structure
SCHEMANAME |
CHAR(32) |
Name of the schema |
TABLENAME |
CHAR(32) |
Name of the table |
USEDSIZE |
FIXED(22) |
Space used by the table (KB) |
ROWCOUNT |
FIXED(20) |
Number of rows in the table |