Compiler Options Use Option(). You might need to do #exe {Option();}. OPTf_GLOBALS_ON_DATA_HEAP without this option, global vars are placed in the code heap which is limited to 2Gig. In AOT modules, global vars take-up room in the .BIN file, so you might want to use this option, instead. You might wish to turn it on and off around specific vars. A disadvantage of data heap global vars in AOT modules is they can't be initialized. OPTf_EXTERNS_TO_IMPORTS and OPTf_KEEP_PRIVATE are strange options, you'll never need. They're to allow the same header file for Kernel to act as externs when compiling itself and imports when compiled by AOT modules. OPTf_WARN_UNUSED_VAR warning if unused var. It is applied to functions. OPTf_WARN_PAREN warning if parenthesis are not needed. OPTf_WARN_DUP_TYPES warning if dup local var type statements. OPTf_WARN_HEADER_MISMATCH warning if fun header does not match. OPTf_NO_REG_VAR forces all function local vars to the stack not regs. Applied to functions. OPTf_NO_BUILTIN_CONST Disable 10-byte float consts for pi, log2_10, log10_2, loge_2. Applied to functions.