Memory Management

SAP memory (Global Memory): - is available to a user during the entire duration of a terminal session. Its contents are retained across transaction boundaries as well as external and internal sessions.

External session: - when user logs on to R/3 system, the system creates a new terminal session called external session. E.g. System  Create Session.

Internal session: - created by calling a transaction (with CALL TRANSACTION), a dialog module (with CALL DIALOG) or a report (with SUBMIT or RETURN).

For external session: - internal sessions are allowed.

Roll area: - Data areas of used programs are created in roll areas for each internal session.

Posting data between internal sessions: - EXPORT TO MEMORY and IMPORT FROM MEMORY.

Main program group: - Created when exporting an internal session.

Additional program group: - If a function module belonging to a function group not so far loaded, additional program group is created.

Subroutine call: - When external subroutine is called, system loads the relevant program and adds it to the program group of calling program.

Work areas: - Both table & common workareas with the same name are created once for each program group and then shared by all programs in the group.

List system: - Consists of basic list and all details list belonging to basic list assigned to exactly one screen level.

User interface: - Only program has its own user interface. Internal sessions interface is initially empty. Special user interface has to be activated using SET PF-STATUS statement.

ABAP/4 memory: - Retained only during the lifetime of an external session.

Data cluster: - Group of several data objects.

Data objects: - Units of data, which a program processes at runtime.