Compiler Options Use Option(). You might need to do #exe {Option();}. OPTf_GLOBALS_ON_DATA_HEAP without this option, global variables are placed in the code heap which is limited to 2Gig. In AOT modules, global variables take-up room in the .ZXE file, so you might want to use this option, instead. You might wish to turn it on and off around specific variables. A disadvantage of data heap global variables 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 variable. It is applied to functions. OPTf_WARN_PAREN warning if parenthesis are not needed. OPTf_WARN_DUP_TYPES warning if duplicate local variable type statements. OPTf_WARN_HEADER_MISMATCH warning if function header does not match. OPTf_NO_REG_VAR forces all function local variables to the stack not registers. Applied to functions. OPTf_NO_BUILTIN_CONST Disable 10-byte float consts for pi, log2_10, log10_2, loge_2. Applied to functions.