Tablespace utilization in db2 (percentage of tablespaces)
You can use list tablespaces show detail (you need to be connected to the database for the show detail clause). This will show you the amount of disk (in bytes if I'm not mistaken) available to the tablespace, the amount used, and the amount "claimed" (known as the "high water mark"). Claimed vs used can differ at times. Sometime after massive deletes and even a REORG the amount of the tablespace used is significantly reduced, but if the high water mark is high, then DB2 still has laid claim to this disk and not released it back to the OS.