Maybe this will help for starters. This is for DB2 on z/OS and shows the open segments for all AGs. shows us % used.
SELECT DATE(CURRENT DATE) AS RUN_DATE FROM ONDDB.ARSUSER
WHERE USERID LIKE 'ADMIN';
SELECT SUBSTR(A.NAME,1,10) AS APP_GROUP,
DECIMAL((DECIMAL(S.INS_ROWS,11,2))/
(DECIMAL(S.MAX_ROWS/100.00,11,2)),11,2) PCT_USED,
SUBSTR(S.TABLE_NAME,1,10) AS TABLE_P,
S.AGID, INTEGER(S.MAX_ROWS)
FROM ONDDB.ARSSEG S, ONDDB.ARSAG A
WHERE SUBSTR(S.TABLE_NAME,1,2) <> 'SL'
AND S.AGID = A.AGID
AND S.CLOSED_DATE = 0
ORDER BY A.NAME, S.START_DATE DESC;