the result set from the view and anything that happens during the processing of the view (aggregations, etc) go into spool.
Temp space is primarily used by temporary tables which have a persistent definition in the Data Dictionary but within a given session. Once the session is over, they are discarded.
Now coming to your question. Since view (as mentioned by you are not materialized) don't have a definition in the data dictionary and are not persistent ( they are dynamic), it uses only spool space.
Always remember, work space or answer sets for any SQL always uses SPOOL space.
If you would need materialization, then you could use either join indexes, or insert-select into regular tables (both use perm space).