6947ch02.fm Draft Document for Review April 7, 2004 6:15 pm
50 IBM eServer zSeries 990 Technical Guide
Java application code can either run on a CP or an zAAP. The user can manage the use of
CPs such that Java application code runs only on a CP, only on an zAAP, or on both when
zAAPs are busy.
For the logical flow of a Java code execution on a zAAP, see Figure6-3 on page 139.

Software support

zAAPs do not change the software model number of the z990 server. IBM software product
license charges based on the software model number are not affected by the addition of
zAAPs.
z/OS Version 1.6 is a prerequisite for supporting zAAPs, together with IBM SDK for z/OS,
Java 2 Technology Edition V1. 4.1.
Exploiters of zAAPs include:
򐂰WebsSphere Application Server 5.1 (WAS 5.1)
򐂰CICS/TS 2.3
򐂰DB2 Version 8
򐂰IMS Version 8
򐂰WebSphere WBI for z/OS
System Assist Processors
A System Assist Processor (SAP) is a PU that runs the Channel Subsystem Licensed Internal
Code to control I/O operations.
All SAPs perform I/O operations for all logical partitions. All z990 models have standard SAPs
configured. The IBM 2084 model A08 has two SAPs; the model B16 has four SAPs; the
model C24 has six SAPs; the model D32 has eight SAPs as the standard configuration.
Channel cards are assigned across SAPs to balance SAP utilization and improve I/O
subsystem performance.
A standard SAP configuration provides a very well-balanced system for most environments.
However, there are application environments with very high I/O rates (typically some TPF
environments). In this case, optional additional SAPs can be ordered. Assignment of
additional SAPs can increase the capability of the Channel Subsystem to perform I/O
operations.
In z990 servers, the number of SAPs can be greater than the number of CPs and the number
of used STIs.

Optional additional orderable SAPs

An option available on all models is additional orderable SAPs. These additional SAPs
increase the capacity of the Channel Subsystem to perform I/O operations, usually suggested
for TPF environments. The maximum number of optional additional orderable SAPs depends
on the model and the number of available uncharacterized PUs in the configuration:
򐂰IBM 2084-A08: maximum additional orderable SAPs is 2
򐂰IBM 2084-B16: maximum additional orderable SAPs is 4
򐂰IBM 2084-C24: maximum additional orderable SAPs is 6
򐂰IBM 2084-D32: maximum additional orderable SAPs is 8