What ratio to exchange salary vs sign-on bonus?

Worried about layoff after being last in first out. Want to shield myself for first year and negotiate a fatter sign-on rather than salary (assuming no clawback). For example, if the offer is as follows: Base: 150k -> base: 140k+30k sign-on Tc: 0. Laid off once already (was 165 before) Yoe: 6