
The BIM-EPIC Environment Physical Input/Output Control System and Pre-Open Checking
Chapter 1. Introduction 1-37
Physical Input/Output Control System and Pre-Open Checking
Programs that use physical IOCS cause conflicts with tape and disk management programs.
As the following sections describe, BIM-EPIC doesn’t get control until your program issues a
request to the VSE supervisor for open, end-of-volume/extent, or close.
Physical IOCS programs cause conflicts because they don’t strictly follow most logical IOCS
program conventions. For example, they perform “pre-open checking”: they check to see
what kind of device is to be used to process a dataset before they open it, before BIM-EPIC
can make the assignment. Most PIOCS programs don’t update the DTF with block size,
record size, record count and address of the last record written, so BIM-EPIC can’t find the
necessary information about the dataset at end-of-volume/extent or close.
However, processing controlled datasets with physical IOCS is not difficult. It requires some
special definitions in the JCL and, in some instances, special defaults in the BIM-EPIC dataset
definition (EDD). See 7-35 in this manual for complete requirements.
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