DB2: The transaction log for the database is full, But there is no 'First active log file'
You really should be reading manuals, not "pruning logs". Your database is set up for circular logging, which means there is nothing to "prune". If transactions occasionally require extra log space, increase the value of LOGSECOND. Too many primary logs will slow down the database startup, as they are preallocated. Secondary logs are allocated as needed, they will remain in the active log directory until the database is restarted. 

"Pruning logs" will not affect the amount of active log space (with one exception that I will mention later): it is dictated purely by the sum of LOGPRIMARY and LOGSECOND, multiplied by LOGFILSIZ. If you were using the archive log mode, you would be able to remove older archived log files to free up some disk space, but the amount of active log space would not change. Even then, you would delete logs created prior to the previous backup, not prior to the first active log file.

Only if your archived logs and active logs share the same file system (which is not a good idea in itself), the uncontrolled accumulation of archived logs may prevent the active log space to grow, when necessary, to its configured maximum size.