You _can_ lock a table via the LOCK TABLE statement but there is no LOCK
INDEX statement. DB2 will lock as much of an index as it needs to but your
application cannot specifically request a lock on an index.

--
Rhino

Depending on isolation level and the actual index used in the query, locks
are acquired by the engine automatically as needed.  There is no explicit
locking commands except at the table level.

Art S. Kagel