When is the task of dividing the memory done by the OS?

The task of dividing memory is primarily handled by the operating system during the process of memory management, which occurs when a program is loaded into memory. This includes allocating memory for the program's code, data, and stack as well as managing memory for multiple processes running concurrently. The OS employs techniques like paging and segmentation to efficiently allocate and manage memory resources. Additionally, memory division is also adjusted dynamically as processes are created or terminated.