What is the SAS LIBNAME statement and how is it used?

A LIBNAME statement is used in a SAS program to associate a "library reference name" with an external SAS data library whose members include SAS data sets and SAS cataloges. The general form of the SAS LIBNAME statement is:

LIBNAME libref 'lib_path'  ;

Where:

LIBNAME is the SAS language statement used to associate a library reference name with an external SAS data library.
libref is a name used within the SAS program to refer to the external data library defined within the single quotes of the LIBNAME statement.
'lib_path' is the full specification of the SAS data library. In most environments, the entity refered to within the single quotes must exist prior to issuing the LIBNAME statement.
Note: If a data set is defined or used without specifying a "LIBNAME", the default LIBNAME of "WORK" is assumed. When "WORK" data sets are created during a SAS job, they are typically deleted when you exit from the SAS environment.
- In PC Windows (3.1, 95, and NT) environments, the SAS Data Library is the name of a subdirectory. If the library is not a subdirectory of the default directory, you must specify the full path for the data library. For example, the following LIBNAME statement will associate library reference 'anyname' with the SAS data library 'd:\lib_path\mydata\test.dat':
```
    LIBNAME  anyname  'd:\lib_path\mydata\test.dat' ;
```
- In UNIX, environments, the SAS Data Library is the name of a subdirectory. If the library is not a subdirectory of the default directory, you must specify the full path for the data library. For example, the following LIBNAME statement will associate library reference 'anyname' with the SAS data library '/home/userid/lib_path/mydata':
```
    LIBNAME  anyname  '/home/userid/lib_path/mydata' ;
```
- In the Macintosh, environments, the SAS Data Library is the name of a folder If the library is not a subdirectory of the default folder, you must specify the full folder path for the data library. For example, the following LIBNAME statement will associate library reference 'anyname' with the SAS data library in the folder mydata contained within the folder lib_path within the drive 'Macintosh HD':
```
    LIBNAME  anyname  'Macintosh HD:lib_path:mydata' ;
```
- If you are using the mainframe MVS System, you can use either the LIBNAME statement in your SAS program or a DD statement in the JCL to assign a library reference name to the SAS data library. See Using SAS Data Sets in the MVS Environment for additional information.
- In VM/CMS, filemode 'A' is assumed as the default SAS data library. In this environment, you only need to specify a LIBNAME statement if the SAS data library refers to a different minidisk. If you are using minidisk 'D' for your SAS data library, you could use the following LIBNAME statement:
```
    LIBNAME  anyname  'D' ;
```
  Note: The VTVM1 System was discontinued Dec. 1st, 1999.