Create new Read Only user on DB2 on the whole database
There is no read only privilege on a database in DB2. You will need to grant SELECT privileges on specific tables, preferably via a role to avoid doing this multiple times.


Create a new database role, e.g. create role readonly.
Grant SELECT privileges on the required tables to that role: 
grant select on myschema.mytable to role readonly.
Create a new user in the operating system, e.g. # mkuser newuser. 
Grant the role to the user: grant role readonly to user newuser.


Note that the new user will likely need to change the initial password before he or she can connect to the database.