Read the following passage and answer the question.
"City agencies are required to post all job vacancies on the NYC Careers website for a minimum of five business days before making a hiring decision.
For titles covered under civil service law, agencies must hire from the appropriate eligible list rather than posting externally.
Agencies may request a waiver from DCAS if no eligible list exists for the title."
When may a city agency request a waiver from DCAS regarding civil service hiring?