You can define a feild just as you regular would up to 32,767 in lenght.
When running in debug it will only show you the first 1024 bytes. You have to manually override that to see more information in debug. Not sure which debug you are using here is an exmaple of green screen command in debug:
<b>eval Field:C 2000</b> Will show you the first 2000 bytes of the field in character form.
<b>eval Field:X 2000</b> Will show you the first 2000 bytes in hex form.
Of course you can increase the size of the number to display more data.