I would not set autocommit to true.
Datawindow selects are supposed to be amended with a for read only. (From vague memory)
A crude work-around would be to issue a Rollback (or commit) in the retrieveend event of your datawindow and datastore ancestor.
Also check if you have any cursors without a for read only or with no commit/rollback afterwards..
This may be of help if you haven't seen it:
http://help.sap.com/Download/Multimedia/ASE_16.0/ptLocking.pdf
You never know there might be a new database option in ASE 16 you can set which happens to default unfavourably.