This document summarizes the new zIIP Support feature for XCOM Data Transport, the new parameters introduced to support it, requirements to use it and answers a few basic questions about it.
Component: XCOM Data Transport for z/OS
What is zIIP?
In IBM System z9 (and later) mainframes, the System z Integrated Information Processor is a special purpose processor. zIIP is intended to free up general computing capacity and lower the overall cost of computing for CPU intensive workloads.
What workloads are offloaded?
Initially, data compression and decompression functions are offloaded to zIIP when available and feasible, as they are highly CPU intensive functions.
Why should I use zIIP support?
The goal of utilizing zIIP is to reduce CPU utilization and the costs that are associated with that utilization. Given that data compression accounts for a significant portion of CPU utilization for a data transfer, moving this processing to a zIIP reduces utilization and costs.
What are the requirements for using zIIP Support?
What new parameters have been added for zIIP support?
By default, XCOM uses zIIP support automatically providing that the zIIP Enablement Service is available to load.
What facilities are available to monitor zIIP usage?
The ZIIP STATUS modify command is automatically issued on startup and termination of the XCOM Server and XCOMJOB TYPE=EXECUTE job start and termination.
For each transfer, statistics about CPU and zIIP usage are written into the history record and SMF record. This data can then be reported on through a TYPE=HISTORY job and/or supplied CA Easytrieve reports.
XCOM doesn't support offloading SSL processing to zIIP. Even then, zIIP is only used if there is no zEDC present on the system, and the user is not using a ZLIB compression algorithm.
The XCOM SSL processing uses LE/C which makes it incompatible with using zIIP. There are certain SSL algorithms that can use ICSF (a hardware-based encryption processor add-on) for encryption. This offloads encryption processing from being software-based and thereby uses less CPU.
ICSF usage is automatic when certain algorithms are used by System SSL.