You have too many open cursors. NCOCI8 opens cursor each time, when call to Open / Prepare happens. You have follows options to solve this issue:

1. Close and UnPrepare unused TOCIQuery / TOCIStoredProc (see Q 5.1); 
2. Set OPEN_CURSORS to some greater value 
3. Set TOCIDataSet.Disconnectable = True for datasets, that NCOCI8 can Close/Unprepare without problems. And set TOCIDatabase.MaxCursors to maximum allowed count of open cursors. When count of prepared TOCIDataSet will grow up to TOCIDatabase.MaxCursors, NCOCI8 will run automatic dataset disconnection process.