Chapter 21: Understanding the S36 Environment

When the AS/400 was being designed, one of the key features in the plan was to make it possible for the AS/400 to run S/36 software with as little modification as possible. Because the two machines differ so much in their architecture, however, it was necessary to create a special environment that would closely mimic the S/36 architecture. The result of this quest is the S/36 Execution Environment, which can be abbreviated as S/36EE or S/36E.

The S/36E is important because it allows i5 installations to continue to run old, yet dependable applications without spending time and money updating those applications to newer application development models. This chapter gives a basic overview of the S/36E and how it fits into i5/OS.

Libraries and Objects

The concept of object is paramount on the i5. Practically everything you can manipulate, including libraries, is an object of some kind. On the i5, all objects are contained in libraries. An AS/400 library can contain executable programs, data areas, database files, commands, and objects of many other types. A System/36 library, on the other hand, contains source code, object code, and Operations Control Language (OCL) scripts. OCL is the S/36 counterpart to CL, but is interpreted rather than compiled. Data objectsfiles and foldersare not stored in libraries.

The difference is important. Data files are unique on the S/36. If you create a file named VENDORS, no other file can have that name (unless you use date-differentiated files, but that is another subject). In contrast, you can create many files, all named VENDORS, on the i5, if you put them in different libraries.

Because database objects must reside in libraries on the i5, S/36E disk files are stored in a library. You can use any library you wish, but IBMs default name is QS36F.