To display Parameter Changes:
Alternatively, use transaction code ST04.
This section lets you display the current and historical settings of the
init<SID>.ora parameters, as well as the date they were changed. If you compare the changes in the database history ( Performance Database (Oracle)) with the parameter changes performed, you can roughly work out what effect the parameter change has had.
Note that changes to parameters do not take effect until the database instance is restarted. Refer to the relevant Oracle documentation for more information.
See also:
Important init.ora Parameters (Oracle)