Welcome aboard. Please maintain a professional standard of written English here on DSXchange. This will help those whose first language is not English.
Can you be more explicit? I understand that you want to set environment variables from a DataStage job. If that's correct, simply execute an appropriate command or pipeline of commands. For example set MYVAR=#valuetoset# You could execute this command (for example, still) via ExecDOS as an after-job...
You don't need a routine. You can use a DataStage job. Pick up the value and stick it in a file or (better) in that job's user status area. (OK, you will need a two-line routine for that, but the code exists on DSXchange.) Pick up the value of the user status area when assigning the value to the job...
A Lookup stage still performs a join - by default a left outer join, but this can be an inner join if the Lookup Failed rule is set to "Drop". Had I meant a Join stage the word would have had a capital "J". In that context please re-read my earlier post, particularly about using a key-based partitio...
In earlier versions of DataStage these stage types were called the RTI ("real time interface") input and output stages; you may still encounter that terminology. Simplistically: Regular job source_stage ---> processing_stages ---> target_stage Job to be deployed as web service WISD_input_stage ---> ...