WHOLE CHARACTER
堂táng
a hall; the main room; cousins through the father's side; an old court or official hall; measure word for lessons; sets of furniture
堂 is a big hall: 礼堂, 课堂, 食堂. 土 is the earth base; 尚 is the old sound side.
The detailed entry's account: ZDIC: 形声，从土，尚声 — 尚 is the sound side (also carrying the 'high' sense) and 土 the earth base. The header's short 字形分析 string orders the two names differently; the detailed account is followed. The written top is 尚 reduced (its 口 does not appear).
TOP: THE REDUCED SOUND SIDE 尚 (SHÀNG)
尚shàng
still; yet; to esteem (literary)
A standalone character (shàng, still; to esteem); when a character keeps it as a piece, the sound role is stated on that character's page.
In 堂: top: the reduced sound side 尚 (shàng) A historical sound side, not a modern hint: táng shares only the final -ang with shàng; the initials (t-/sh-) and tones (2/4) differ. The written top drops 尚's 口.
BOTTOM: THE EARTH BASE, NAMED BY ZDIC
土tǔ
earth; soil
Repeated in 垚.
In 堂: bottom: the earth base, named by ZDIC Shown with its documented or clearly limited role.