I believe its in the JES Queue class assignment of the output, and there is an ARSLOAD started task which monitors that class.
//ARSLOAD EXEC PGM=ARSLOAD,REGION=0M,TIME=NOLIMIT,
// PARM=('/-h ARSDBASE -c /ars/tmp -C 0 -E -A WRITER -fv \
// -U /etc/ars/arsload.cfg ')
The value after "-C", 0 here, is the JES class to pick up .
The value after "-A" is the portion of the JES name identifying the application.