The db_keep_cache_size sets the size of the pool to contain tables that you want to be kept cached at all times. After setting this value, an alter table statement must be run so that the tables are cached in the keep pool after the first time they are accessed.
To set the db_keep_cache_size to
500M type the following:
alter system set db_keep_cache_size=500M;
Then put the proper objects in
the keep pool such as: