DB2 v9.5 ESE on AIX v6.1

I need to have a database with
Database code page = 819
Database code set = ISO8859-1

so I create a database with this codeset, but when I restore database (on v9.5) from backup file (from v8.2) into this database, codeset changes to:
Database code page = 850
Database code set = IBM-850

which is the codeset of the database in backup image.

What can I do to keep same codeset/page (819)?

You will need to use a backup of the database whose codeset is 819.

Backup/Restore only copies the data as-is and does not apply any kind of modifications/reorganizations. So it is just a binary copy.

If you want to modify the code page, you need to export/import the data.