IAM Performance

Increase the numbers of buffers that can be specified when using 64-bit addressable storage for IAM buffers. This includes moving the IAM Buffer Table to 64-bit virtual storage for increased capacity and 31-bit storage constraint relief. This enhancement effectively allows for entire small to moderately sized files to be kept in 64-bit virtual storage thus vastly reducing the amount of I/O needed to read and write data from and to such files.

The IAM Overflow Index search algorithm has been improved by using a tree structure, rather than a linear search, which results in lower CPU usage and improved overflow record processing performance when a large number of Overflow Index records are accessed randomly. This new feature is exploited when a new ACCESS Override is used named EXPOVIX.

IAM/RLS and IAM/PLEX Journaling

IAM/RLS and IAM/PLEX z/OS System Logger Logstream journaling will now write journal records in IBM data replication format. As of IAM release 9.3, IAM has had the ability for batch jobs to do file update journaling in IBM Data Replication format and with this enhancement, when an IAM data set is under IAM/RLS or IAM/PLEX control, it can also be a source file for IBM data replication. With this enhancement, IAM datasets can be processed by IBM GDPS Active-Active VSAM data replication products or by IBM Infosphere Change Data Capture (CDC) products.

IAM File Load Simulation

This new feature provides the capability to perform an IAM file load operation without actually writing out any data records. The IAMINFO report produced by the file load simulation will allow a user to check statistics as if the data had been written. This can aid in decision making situations such as when a very large data set is being broken up into several smaller data sets. For example, a user could determine what key ranges to assign to each smaller data set.