Overview

The Data Division is subdivided into the following sections:

1. File Section
2. Working-Storage Section
3.  Thread-Local-Storage Section
4.  Object-Storage Section
5.  Local-Storage Section
6. Linkage Section
7. Report Section
8.  Screen Section.

The File Section defines the structure of data files. Each file is defined by a file description entry and one or more record descriptions. Record descriptions are written immediately following the file description entry.

The Working-Storage Section describes records and noncontiguous data items which are not part of external data files but are developed and processed internally. It also describes data items whose values are assigned in the source text and do not change during execution.

  The Thread-Local-Storage Section describes data which is unique to each thread, and is persistent across calls. Thread-local-storage can be viewed as thread-specific working-storage. This is useful for resolving contention problems in most reentrant programs. In many cases, a non-file-handling program can be made completely reentrant by simply changing the WORKING-STORAGE SECTION header to a THREAD-LOCAL-STORAGE SECTION header.

  The Object-Storage Section describes class object data and instance object data. Its structure is the same as the Linkage and Working-Storage Sections.

  The Local-Storage Section identifies a program as eligible for recursion. The Local-Storage Section can also be specified in a method, which is also eligible for recursion. A separate copy of the Local-Storage Section is created each time the runtime element is activated and exists only during the lifetime of that runtime element.

The Linkage Section appears in a source element that can be activated by another source element. It describes data items that are to be referred to by both the activating and the activated elements. Its structure is the same as the Working-Storage Section.

The Report Section contains one or more report description entries (RD entries), each of which forms the complete description of a report.

  The Screen Section defines the attributes of the screens. It offers the facility to specify the exact location of fields when they are displayed on the screen as well as to control certain console features during an ACCEPT or DISPLAY operation.

  Data records and items that are described in the same way have the same type. The descriptions of such items can be conveniently manipulated by declaring a type definition. A type definition can appear in the Working-Storage and Linkage Sections. A type definition in a call prototype may be referenced in a program definition.