Operating Systems

This article examines several areas fthat should be considered when ftuning Local Shared Resource (LSR) pools. The main performance objective when tuning CICS LSR pools is to improve the lookaside hit ratios, but there are other tuning areas that are generally overlooked. In this article, we will attempt to answer the questions asked in many CICS tuning classes such as:

• How many pools should I define?

• Are there any advantages to defining multiple pools?

• How many strings should I define?

• How do I know when a file is monopolizing a pool and should be segregated into another pool?

We’ll cover how to improve the look-aside hit ratios and additional areas you can tune to improve performance of CICS LSR pools and response times. Applying these recommendations has helped some organizations improve online response time and reduce overall CPU use attributed to CICS. Given the better look-aside algorithm available in LSR, it’s best to assign most VSAM files to LSR buffering in CICS. We’ll review areas you should watch when tuning LSR files (but not general VSAM tuning or programming techniques that also could be quite helpful in improving file performance in an online environment).

CICS Buffering

CICS uses three basic buffering techniques:

• Non-Shared Resources (NSR)

• Record Level Sharing (RLS)

6 Pages