SAP Parameter ztta/roll_extension - Quota for Extended Memory per user context


Short text
Quota for Extended Memory

Parameter description
This values specifies the amount of memory in bytes that a user contextcan allocate to extended memory. The value refers to the amount ofmemory that an external session (=SAP window) allocates.
If the entered value is exceeded, memory is first allocated from theroll area again, until this is full, and then heap memory is allocated(see ztta/roll_area ).
(Data in the roll area is copied at context change. When heap memory isallocated, the assignment of this work process to this user context isfixed, and it is no longer available for other user contexts (PRIVmode).) )
If you set the value too high, an individual user could cause abottleneck in the extended memory by increasing the size of his or heruser context. Other smaller user contexts would therefore take workprocesses into PRIV mode, before their permitted quota was exhausted.
- Minimize number of work processes in PRIV mode.
- Distribute extended memory fairly.

Parameter unit

Default value
250000000 (250 MB) (Others)
2000000000 (2GB) (Microsoft Windows NT)
Remove the quota, because dynamic extension means that there is alwayssufficient extended memory.

Default Value
250000000 (250MB) Lower if extended memory is scarce and must bedistributed more fairly.
Microsoft Windows NT
2000000000 (2GB) = Remove the quota. The quota for a user context in theextended memory is em/address_space_MB(reserved memory area for extended memory in the work process)

Who is allowed
The customer. No manual maintenance is necessary for Microsoft WindowsNT.

Other parameter
ztta/roll_extension only takes effect if its value is lower thanem/initial_size_MB. Increasing the size of
ztta/roll_first saves extended memory, butleads to an increased load during the context switch.

Limitation for os
See above

Limitation for db