Sitting and reading Salaatut-Tasbeeh

Assalam o alaikum,
Respected Mufti Sahab, I read Salatut Tasbeeh occasionally, Though I read the namaz by standing like I read other namaz’s like fardh,wajib etc. I want to ask that this is a nafil namaz so can one sit and read the whole namaz without any shari excuse and count tasbeeh as one counts while one is standing and reading namaz. Or this namaz can only be read while standing.

Jazzak Allah!