Free space determination in dbspace for 4.10

How is the free space determined within a dbspace with version 4.10. Two problems began which do not appear to be caused by the task that is failing (error 271 loading a table that has previously loaded successfully with the same data; error 1328 executing 4GL programs that have previously executed successfully). I suspect these problems are related to a lack of space. My documentation is for a newer release, and my administrative knowledge of Informix is very limited. Any assistance will be greatly appreciated.