How do you change the states of the tablespaces.
How can I put the tablespace in the offline mode ?
What are the implications of doing that?

db2 "alter tablespace tablespace-name switch offline"

to put it back online you would issue the same db2 command but
use the keyword online instead of offline.

Implications-
to perform certain db2 maintenance tasks it is useful to take the tablespace offline depends on what you are trying to do. You will not have access to insert or update data or tables located on the tablespace that you take offline.

Hope this helps
Scott