Information
The DIAGLEVEL parameter specifies the type of diagnostic errors that will be recorded in the db2diag.log file. It is recommended that the DIAGLEVEL parameter be set to at least 3.
Rationale:
The recommended DIAGLEVEL setting is 3, but any value greater than 3 is also acceptable. A value of at least 3 will allow the Db2 instance to capture all errors and warnings that occur on the system.
Solution
Attach to the Db2 instance
db2 => attach to <db2instance>
Run the following command:
db2 => update database manager configuration using diaglevel 3