The DataStage "View Data" facility has caused more perceived NLS problems than any other part of the tool - it is not capable of correctly displaying NLS data and shouldn't be used to see if NLS is working or not. Did you "view data" to see the character or use another tools?
When you read from Oracle into DataStage you need to specify the correct NLS map - the one Oracle is actually using. The same needs to be done when writing to your target. If either one of these settings is not done correctly then it is possible that characters don't get mapped the way you expect.
What are your Oracle source settings?
That parameter doesn't have to do with NLS; if your uvconfig has no NLS entries then any character conversion is not being done by DataStage. Read your Oracle and write to a text file, then look at the value in the text file (not with View Data in DataStage) to see if has been altered. What is your NLS_LANG environment setting?