If the idea is to create an ordering of the jobs, so the sequence range can have holes in the range you can use an autonumber attribute.
The use this attribute to combine this with the store and branch to create the complete id.
This will not cause issues with concurrency, but does allow for numbers to be missed as the numbers are claimed on the create of the request and if the user decides not to commit the request the number is lost.
But as I said if the idea is to create a unique number that is used for sorting/ordering of the records this will work fine.