4D has a database parameter that limits the number of logs maintained. This is to prevent the saturation of the hard drive if all logs are maintained. This parameter is called the Circular log limiation parameter.

By default it is set to 50 when the database is started. The feature maintains the latest number of logs for each log type upto the parameter's value.
With 50, when the 51st log is generated, the 1st log is deleted. Next when the 52nd log is generated, the 2nd log is deleted. This will limit the max number of space used on the hard drive.

This setting can only be changed with the command SET DATABASE PARAMETER and passing the Circular log limitation selector as the first parameter and the number of logs to keep as the second parameter. 0 can be passed to keep all logs.