The "Tax Computation Worksheet" is on page 79 of the Form 1040 instructions:
https://www.irs.gov/pub/irs-pdf/i1040gi.pdf
As you say, that's an internal calculation, and a fairly simple one, so the program isn't cluttered up with that worksheet. If using that Wks you come up with a different amount than TT did on the Sch D Tax Wks line 42, you'll have to provide your Sch D Tax Wks line 19 amount and filing status so we can double-check.
