Can I sacrifice a permanent to pay an ability cost while the permanent's spell is still on the stack?
A card on the stack is not a permanent, so you may not sacrifice it.

When a card refers to a permanent type, like "artifact" or "creature," it refers only to permanents &mdash; meaning a card on the battlefield. Note that this includes the Lightning Bolt spell in your question &mdash; you can't sacrifice the creature until it is on the battlefield, but your opponent can't Bolt the creature until it is on the battlefield, either.

Cards in other zones are referred to as cards &mdash; e.g. Unburial Rites: "Return target creature card from your graveyard to the battlefield." &mdash; or spells if they're on the stack &mdash; e.g. Essence Scatter: "Counter target creature spell." (Compare to Murder, which affects creatures on the battlefield: "Destroy target creature.")