DB/2 for i does not appear to perform any timezone conversion according to the following test:
CHGSYSVAL SYSVAL(QTIMZON) VALUE(QN0500EST3)
CREATE TABLE QTEMP/TEST AS (SELECT NOW() TS FROM SYSIBM/SYSDUMMY1) WITH DATA
SELECT TS FROM QTEMP/TEST
....+....1....+....2....+.
TS
2014-04-21-17.52.17.813498
CHGSYSVAL SYSVAL(QTIMZON) VALUE(Q0000UTC)
SELECT TS FROM QTEMP/TEST
....+....1....+....2....+.
TS
2014-04-21-17.52.17.813498