Previous topic |
Next topic |
Contents |
Contact z/OS |
Library |
PDF
Compressed Data z/OS DFSMS Using Data Sets SC23-6855-00 |
|
To use compression, a data set must be in extended format. Only
extended-format key-sequenced data sets can be compressed. The compressed
data records have a slightly different format than logical records
in a data set that will not hold compressed data. This results in
several incompatibilities that can affect the definition of the data
set or access to records in the data set:
In addition to these incompatibilities, the data set must meet
certain requirements to permit compression at the time it is allocated:
Spanned record data sets require the key offset plus the key length to be less than or equal to the control interval size minus fifteen. These specifications regarding the key apply to alternate keys as well as primary keys. Compressed data sets cannot be accessed using control interval (CI) processing except for VERIFY and VERIFY REFRESH processing and may not be opened for improved control interval (ICI) processing. A compressed data set can be created using the LIKE keyword and not just using a data class. |
Copyright IBM Corporation 1990, 2014
|