ESP12E: Save Data into Flash Memory

Perfect, exactly what i was looking for.

Size can be anywhere between 4 and 4096 byte

.
let's assume my programmcode is 7kb. In this case, the size shouldn't be 4096, right? Something like
4096 bytes - size of program in bytes
Or should i better leave more space? Is this necessary? Like reserving 4000 bytes instead of 4089/4096 bytes.