I don't believe this functionality is available until V7 fixpack 3
From the fixpack
7.6.6 On Demand Log Archive
DB2 now supports the closing (and, if the user exit option is enabled, the archiving) of the active log for a recoverable database at any time. This llows you to collect a complete set of log files up to a known point, and
then to use these log files to update a standby database.
Note:
On demand log archiving does not guarantee the log files will be archived immediately; it truncates the log file and issues an archive request, but it is still subject to delays associated with the user exit program
You can initiate on demand log archiving by invoking the new DB2 ARCHIVE LOG command, or by calling the new db2ArchiveLog API.