LOGDIR parameter    ==  LOGDIR=dirPath
                    --  default: LOGDIR='${VARDIR}/log'
                    --  v10-default: LOGDIR='log[date+/y%y/m%m/%d]'

The default directory where log files are placed. From the version 10, by default, log files became devided by year, month and day, as 'DGROOT/log/y14/m08/20/80.http' for example.