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98 The second method of setting the Heap Limit is to specify the desired size of the heap using the directive Option HeapSize in your Main module or by using the compiler option –-heap-size. The Heap Limit is set by subtracting the specified value from the address one past the end of RAM. For devices that have external RAM, the end of RAM is determined at startup. If you have external RAM, you may specify that all of the external RAM should be used for the heap by specifying the heap size using the special values 65535 or &HFFFF. The final method for setting the Heap Limit is to specify an absolute address using the directive Option HeapLimit in your Main module or by using the compiler option –-heap-limit. This method is recommended for use only by advanced programmers who understand completely how memory is allocated in a native ZBasic application. 4.7 Creating and Using Object Libraries It is often useful to create a library of code elements from which the essential elements are drawn when building an application. Such libraries can then be easily reused in several applications or distributed to other ZBasic users for use in building their applications. The ZBasic compiler supports the creation of object libraries only for native mode devices. To instruct the ZBasic compiler to build a library instead of building a downloadable file as it normally does, add the option –-create-library to your project file. If no filename is specified with that option, the library name will be same as the project name but with the extension .a. The compiler will create an additional file containing ZBasic declarations for all of the public elements in the library; this file with have the same name as the library but with the extension .inc. It is important to note that none of the ZBasic files compiled into the library should have a public subroutine named Main(). To use the library in a ZBasic application, it is only necessary to add the name of the declarations file to that application’s project file or, alternately, to include the declarations file in one of your modules (e.g. the Main() module) using the #include directive. Generally, the declarations file and the library file should be kept in the same directory. The declarations file contains a directive to tell the compiler the name of the corresponding library file – that’s why it doesn’t need to be explicitly mentioned. If you create library files to distribute to others, you only need to supply the declarations file and the library file. The source code for the library needn’t be distributed if you’d like to keep it proprietary.