SAS Companion for the CMS Environment

Working with SAS Files in Tape Format on Disk

In the CMS environment, SAS libraries can be stored on disk in tape format. Keep the limitations of sequential files in mind when choosing between tape format and disk format. Tape format on disk is not recommended because of the loss of functionality. For example, because the files in the SAS library cannot be randomly accessed, SAS data sets cannot be indexed nor can catalogs be used. Despite the limitation, tape-format SAS libraries can be processed by SAS under OS/390 and VSE.

As with SAS files on tape, each tape-format SAS file on disk is stored as a single file, as long as each SAS file has a unique libref. If you write multiple SAS files on disk in tape format using the same libref, they are all written to one sequential file, making access to a particular SAS file difficult.

To force tape format for a SAS library on disk, specify the sequential engine in the LIBNAME statement. The form of the LIBNAME statement to use is

LIBNAME libref TAPE <'physical-name'>;

Examples

The following example causes the library to be written to the first R/W disk, using the default filename SASTAPE:
```
libname raisins tape;
```
Be sure to include a physical-name if you want the file to be on a minidisk other than the default. For example, if you want the file to be written on your M-disk, use this LIBNAME statement:
```
libname raisins tape 'm';
```

The following example writes two tape-format SAS data files in separate libraries on the A-disk:

libname day1 tape 'a';
data day1.earn;
   input branch $ 1-20 
      dept 22-24 @26 revenue 10.;
   cards;
data lines
;

libname day2 tape 'a';

data day2.earn;
   input branch $ 1-20 
      dept 22-24 @26 revenue 10.;
   cards;
data lines
;

The next example reads the tape-format SAS data sets that were created in the previous example.

proc print data=day1.earn;
   id branch;
   var revenue dept;
run;
proc print data=day2.earn;
   id branch;
   var revenue dept;
run;

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