VSAM dynamic access read option VSAMDYNAMICDIR
To change the dynamic access method of VSAM to a direct read-by-key request to the VSAM engine, you must specify the COBOL runtime option VSAMDYNAMICDIR. This alternate logic path takes advantage of IBM®'s hardware disk systems that make use of zHyperLink. zHyperLink improves application response time, which cuts I/O-sensitive workload response times significantly. If you do not change the dynamic access method, the default runtime behavior is to point to a record by key and then read records sequentially.
To use this feature, create the IGZUOPT (for AMODE 31) or IGZQUOPT (for AMODE 64) COBOL runtime option module that will use the VSAMDYNMAICDIR=ON option.
If VSAMDYNAMICDIR is not
specified, the default is VSAMDYNAMICDIR=OFF.
IGZXOPT VSAMDYNAMICDIR=ON | OFF
For more details, see Building IGZUOPT and IGZQUOPT runtime option control block.
See the sample JCL IGZ5OPT in the Language Environment® sample data set
to learn how to turn on VSAMDYNAMICDIR.