ztta/roll_area: Roll Area

Use

Total size of the roll area in bytes.

A part of this area (in the graphic Roll area 1) is allocated a user context at the beginning. Its size is defined in ztta/roll_first. The partial area is for the data that must be contained in the roll area. During a user context change, this data is "rolled" (copied) into and out of a work process. If ztta/roll_area is larger than ztta/roll_first, the additional space makes a second part available (Roll area 2).

If the user context cannot be allocated more Extended Memory, this second part of the roll area is available for the dialog processes (see Allocating Memory for User Contexts).

By specifying a higher value for ztta/roll_area than for ztta/roll_first, you avoid allocating local private memory as soon as the set limits of the R/3 Extended Memory are reached. The remaining roll memory therefore serves as the last buffer before a user context has to allocate heap memory.

This pushes back the point in time at which a work process is switched to PRIV mode (see Private Memory). Although there advantages to this procedure, there are also the following disadvantages: The copying procedure is much slower for storing data in the roll area for changing work process contexts. The copy necessary for the roll area during context changes is slower than the allocation procedure used for the context change with R/3 Extended Memory. Therefore, increasing the roll area memory slows down the context change.

Goal:

Reduce data transfer to a minimum using copy procedures during context changes (value closer to ztta/roll_first), higher values avoid problems however (address space, swap space, operating system paging, work process change to PRIV mode, if the R/3 Extended Memory limit is reached).

Integration

• rdisp/ROLL_SHM: Should be adjusted if you change ztta/roll_area.
• rdisp/ROLL_MAXFS: Must be adjusted if you change ztta/roll_area.
• ztta/roll_area: Must be larger than or the same size as ztta/roll_first.

Activities

Unit: Bytes

Default value: 6500000 (6.5 MB)

Recommended value: UNIX: 6500000 (6.5 MB) 1000000 (1 MB) is the minimum size. Under IBM AS/400 167731120 (16 MB), under Windows NT: 1000000 (1 MB).

Changes: Under IBM AS/400, only SAP is allowed to change this value. Under UNIX and Microsoft Windows, you can only change this parameter value in accordance with the configuration examples (Contents button) or for Windows NT in accordance with the information in Maximum Use of Extended Memory.