UB4MAXVAL - cheeyoung/sqlplus-public GitHub Wiki

2.54 CONTROL_FILE_RECORD_KEEP_TIME

If the number of reusable records in the control file exceeds the circular reuse record limit UB4MAXVAL, then reusable records will be overwritten even if CONTROL_FILE_RECORD_KEEP_TIME has not elapsed. UB4MAXVAL is defined in the oratypes.h header file, which is found in the public directory. Its value may vary according to the operating system you are using.