Sorry for the naive question. But As I would like to build a function to store parametersin the eeprom I need to be sure not to overwrite string variable allocated via F() primitive
Program code is in flash, not EEPROM. The small amount of EEPROM can be written a byte at a time, flash memory is page-based and only written when uploading a sketch, typically.
Great for memory pinpointing... even a small amount of 1024 bytes (at328) is enough to store parameters.