When set to TRUE, this variable causes the Database Connectors for MSSQL interface to open two connections to any server it connects to. One of those connections performs all the normal COBOL data work (write, rewrite, read next, etc).
The second connection does all the internal work needed by the interface to do its normal work, such as updating the lock tables, testing for locks, etc.
The reason for the configuration variable is that a separate connection to SQL Server requires a separate license from Microsoft.
If you are experiencing frequent deadlocks during record locking or opening of tables, you may be able to solve those by setting this variable to TRUE.