The active log files record transactions that are in progress on the server.
The active log stores all the transactions that have not yet been committed. The active log always contains the most recent log records. If a failure occurs, the changes that were made but not committed are rolled back, and all committed transactions, which might not have been physically written to disk, are reapplied and committed again.
The location and size of the active log are set during initial configuration of a new or upgraded server. You can also set these values by specifying the ACTIVELOGDIRECTORY and the ACTIVELOGSIZE parameters of the DSMSERV FORMAT or DSMSERV LOADFORMAT utilities. Both the location and size can be changed later. To change the size of the active log, see Increasing the size of the active log. To change the location of the active log directory, see Moving only the active log, archive log, or archive failover log.
For information about the space required for the active log directory, see Active and archive log space.