Deciding whether to use a shared library

The decision to use a shared library, should be based on whether it saves space in disk storage and memory. A well-designed shared library almost always saves space. As a general rule, use a shared library when it is available.

To determine what savings are gained from using a shared library, try building the same application with both a non-shared and a shared library, assuming both kinds are available. Then compare the two versions of the application for size and performance. For example:

   $ cat hello.c
   main()
   {
      printf("Hello\n");
   }
   $ cc -o unshared hello.c
   $ cc -o shared hello.c -lc_s
   $ size unshared shared
   unshared: 8680 + 1388 + 2248 = 12316
   shared: 300 + 680 + 2248 = 3228

If the application calls only a few library members, it is possible that using a shared library could take more disk storage or memory. For a more detailed discussion see ``Space considerations''.