This keyword causes the c-tree Server to log the following warning message to CTSTATUS.FCS and to standard output (or the message monitor window on Windows systems) when the current transaction number exceeds the specified transaction number:
WARNING: The current transaction number (####) exceeds the user-defined threshold.
The message is logged every 10000 transactions once this limit has been reached. The TRAN_OVERFLOW_THRESHOLD limit can be set to any value up to 0x3ffffffffffff, which is the highest 6‑byte transaction number that FairCom DB supports.
When FairCom DB supports 6‑byte transaction numbers it does not display transaction overflow warnings until the current transaction number approaches the 6‑byte transaction number limit. But if 4‑byte transaction number files are in use, a key insert or delete will fail if the current transaction number exceeds the 4‑byte transaction number limit (however, FairCom DB will continue operating). This keyword allows the server administrator to determine when the server will issue a warning that its transaction number is approaching the limit.