You don't mention how you plan to display the output. Use ISPF w/hex on?
DISPLAY to SYSOUT?, etc. You also don't mention how you will move the value 10005.0 to the COMP-3 field. I assume if you code it as a literal in a move stmt (without quotes) it will be treated as numeric edited data. If you move it from a data area you must define it as such.
After the move the data you cite will be represented in memory as: