Applies to:

Oracle Server - Enterprise Edition - Version: 8.1.7 to 11.1.0.6
Information in this document applies to any platform.

Goal

A Stored Outline will only be used when the parameter USE_STORED_OUTLINES is set persistently.  If parameter is set  using alter session or by defining in  pfile/spfile  the change is not permanent and will no longer be set after database has been restarted.
A STARTUP trigger needs to be defined in order to make this setting persistent after restart of database

Solution

Create the following trigger to be run on startup of the database:
create or replace trigger enable_outlines_trig
after startup on database
begin
execute immediate('alter system set use_stored_outlines=true');
end;