What happens if I supply a higher voltage than the rated voltage of my jack?
The jacks on DigiKey are rated for 24 V: http://www.digikey.com/product-detail/en/PJ-005A/CP-5-ND/165838

I would not hesitate to use any DC barrel plug at 19V, because that's just not much voltage.  Unless it's a really marginal design, it will be OK.