You retrieve QSAM files, cataloged
or not, by using job control statements or environment
variables.
- Cataloged files
- All data set information, such as volume and space, is stored
in the catalog and file label. All you have to code are the data
set name and a disposition. When you use a DD statement, this is the DSNAME parameter and the DISP parameter. When you use an environment variable, this
is the DSN parameter and one of the parameters OLD, SHR, or MOD.
- Noncataloged files
- Some information is stored in the file label, but you must code
the unit and volume information, and the dsname and disposition.
If you are using JCL, and you created the file in the current
job step or in a previous job step in the current job, you can
refer to the previous DD statement for most of the data set information. You do,
however, need to code DSNAME and DISP.