The control_file_record_keep_time parameter sets the minimum number of days that must have elapsed before a reusable controlfile record slot can be reused. The default is 7 days. If all the slots in a record section are in use and that number of days has not yet elapsed since the timestamp on the earliest entry, then Oracle will dynamically expand the record section (and thus the controlfile too) to make more slots available, up to a maximum of 65535 slots per section, or the controlfile size limit
in alert log if we found "kccrsz: expanded controlfile section"
it is just information message for controlfile is increase in size.
control file contains
Database information (RESETLOGS SCN and their time stamp)
Archive log history
Tablespace and datafile records (filenames, datafile checkpoints, read/write status, offline or not)
Redo threads (current online redo log)
Database's creation date
database name
current archive log mode
Log records (sequence numbers, SCN range in each log)
RMAN catalog
Database block corruption information
Database ID, which is unique to each DB
The size, total number and number of used record are exposed through v$controlfile_record_section.
