Oracle Scheduler - Oracle 10g/11g Data and Database Management Utilities - page 225

The PURGE_LOG job launches a Program named SYS.PURGE_LOG which is defined as
a STORED_PROCEDURE and whose procedure name is DBMS_SCHEDULER.AUTO_PURGE .
This stored program unit receives no arguments and it purges the logs based on
its retention period. The DEFAULT_JOB_CLASS has no explicit retention period
declared, so it takes the default value of 30 days. This should be enough to maintain
a reasonable amount of log history for most practical situations, but as the purge
log job has been defined using the standard DBMS_SCHEDULER infrastructure you can
tailor it to it your particular log retention needs.

Data dictionary related views
The Oracle Scheduler DBA related data dictionary views are:

View Description
DBA_SCHEDULER_CHAINS All Scheduler chains in the database.
DBA_SCHEDULER_CHAIN_RULES All rules from Scheduler chains in the database.
DBA_SCHEDULER_CHAIN_STEPS All steps of Scheduler chains in the database.
DBA_SCHEDULER_GLOBAL_ATTRIBUTE All Scheduler global attributes.
DBA_SCHEDULER_JOBS All Scheduler jobs in the database.
DBA_SCHEDULER_JOB_ARGS All arguments with set values of all Scheduler
jobs in the database.
DBA_SCHEDULER_JOB_CLASSES All Scheduler classes in the database.
DBA_SCHEDULER_JOB_LOG Logged information for all Scheduler jobs.
DBA_SCHEDULER_JOB_RUN_DETAILS The details of a job run.
DBA_SCHEDULER_PROGRAMS All Scheduler programs in the database.
DBA_SCHEDULER_PROGRAM_ARGS All arguments of all Scheduler programs in
the database.
DBA_SCHEDULER_RUNNING_CHAINS All steps of all running chains in the database.
DBA_SCHEDULER_SCHEDULES All schedules in the database.
DBA_SCHEDULER_WINDOWS All Scheduler windows in the database.
DBA_SCHEDULER_WINDOW_DETAILS The details of a window.
DBA_SCHEDULER_WINDOW_GROUPS All Scheduler window groups in the database.
DBA_SCHEDULER_WINDOW_LOG Logged information for all Scheduler windows.
DBA_SCHEDULER_WINGROUP_MEMBERS Members of all Scheduler window groups in
the database.

V$SCHEDULER_RUNNING_JOBS Currently running jobs.

DBA_QUEUE_SCHEDULES

Describes the current schedules for
propagating messages.