In a chloroplast, the stacks of membranous sacs are called

Grana is part of the thykaloid. Each stack of thykaloid (the individual disks) are called grana. Cristae are those twisted, curving-shaped inner membranes in mitochondria where cellular respiration occur. Vacuoles stores food, waste, etc.

Stroma is the fluid-like part in the chloroplast. Thykaloid is contained in the stroma.

So, are the membranous sacs called thykaloid.