A_MSSQL_MAX_CHARACTERS indicates the maximum number of bytes the allows in a table row.
Microsoft SQL Server places a limit on the number of bytes per table row. adheres to this limit, but sometimes it cannot accurately count how many bytes a particular row contains (because of overhead bytes that Microsoft SQL Server adds). This variable enables the developer to set upper bound.
You might want to try reducing this value if a table cannot be created. By reducing the upper bound, you may be able to prevent this problem.
If Microsoft SQL Server increases the maximum number of bytes allowed in a row (in a future release of the product), you can increase the value of this variable to take advantage of the new limit.
The A_MSSQL_MAX_CHARACTERS variable has a default value of 8060.