Does a database parameter value change need bouncing?

You need a quick look whether a db parameter needs bouncing the db.

issys_modifiable column in v$parameter view tells this. False dos not mean you cannot change it with ALTER SYSTEM, means a bouncing. I think this parameter name must be something like "issys_changeable_in_session" :)

issys_modifiable column name is easier to understand, if it is TRUE you can change in session with ALTER SESSION , FALSE then you cannot.

For sample parameters, below SQL Statement which produced this data:

SELECT   name, issys_modifiable
FROM   v$parameter
WHERE   name in ('session_cached_cursors','object_cache_optimal_size','db_cache_size');

NAME	ISSYS_MODIFIABLE	MY COMMENT
db_cache_size	IMMEDIATE	No bouncing needed.
object_cache_optimal_size	DEFERRED	A new connection needed.
session_cached_cursors	FALSE	Bouncing needed.

For more detailed information:

http://download.oracle.com/docs/cd/B19306_01/server.102/b14237/dynviews_2012.htm#REFRN30176