Stackable items are items that only take up one space in a player's inventory not being carried in note form. When multiple stackable items are carried in the inventory, a number is shown on the item's picture to indicate the quantity of items in the stack. Most items stored in the bank will stack, even if they don't stack in a player's inventory. A few exceptions would be brawling gloves, satchels, and the various forms of the morphic tool. Stackable items do not weigh anything, and cannot be withdrawn from the bank as a note.
Stackable items include bait, charms, runes, all arrows, all seeds, notes, and coins. Other stackable items include bolts, bolt tips, darts, dart tips, nails, arrowtips, throwing knives, cannonballs, javelins, throwing axes,feathers, arrow shafts, needles, thread, Purple Sweets, teleport scrolls and teleport tablets. You cannot pick up another item if you already have the maximum stack in your inventory.
Limit of a stack
The maximum number of an item that a player can hold in a stack is 2,147,483,647, as limited by a signed (positive and negative) 32-bit integer, i.e. 231 - 1.
The maximum limit is 2,147,483,647 as java can not recognise numbers over this.