This option sets the size of the stack in bytes and takes arguments in decimal or C-language notation. The /STACK option applies only to an executable file.

The reserve argument specifies the total stack allocation in virtual memory. EDITBIN rounds up the specified value to the nearest 4 bytes.

The optional commit argument is subject to interpretation by the operating system. In Windows NT, Windows 95, and Windows 98, commit specifies the amount of physical memory to allocate at a time. Committed virtual memory causes space to be reserved in the paging file. A higher commit value saves time when the application needs more stack space but increases the memory requirements and possibly startup time.

Reference