Using the SYSDSN Function

The SYSDSN function determines if a specified data set is available for your use. If the data set is available for your use, it returns "OK".

available = SYSDSN('myrexx.exec')
 /* available could be set to "OK"  */

When a data set is not correct as specified or when a data set is not available, the SYSDSN function returns one of the following messages:

• MEMBER SPECIFIED, BUT DATASET IS NOT PARTITIONED
• MEMBER NOT FOUND
• DATASET NOT FOUND
• ERROR PROCESSING REQUESTED DATASET
• PROTECTED DATASET
• VOLUME NOT ON SYSTEM
• UNAVAILABLE DATASET
• INVALID DATASET NAME, data-set-name:
• MISSING DATASET NAME

After a data set is available for use, you may find it useful to get more detailed information. For example, if you later need to invoke a service that requires a specific data set organization, then use the LISTDSI function. For a description of the LISTDSI function, see Using the LISTDSI Function.

When you specify a fully-qualified data set, be sure to use two sets of quotation marks as follows; one set to define a literal string to REXX and the other set to indicate a fully-qualified data set to TSO/E.

x = SYSDSN("'proj5.rexx.exec'")

or

x = SYSDSN('proj5.rexx.exec'')

When you specify a data set that is not fully-qualified and begins with your prefix (usually your user ID), you can use one set of quotation marks or none at all. TSO/E adds your prefix to the data set name whether or not it is enclosed within a set of quotation marks.

x = SYSDSN('myrexx.exec')

or

x = SYSDSN(myrexx.exec)

When you specify a variable that was previously set to a data set name, do not enclose the variable in quotation marks. Quotation marks would prevent the data set name from being substituted for the variable name.

variable = 'myrexx.exec'
x = SYSDSN(variable)

The following example uses the SYSDSN function together with the LISTDSI function to test whether a data set exists and whether it is a partitioned data set:

DO FOREVER
  SAY 'Enter a Data Set Name'
  PARSE UPPER PULL dsname
  IF SYSDSN(dsname) ¬= 'OK' THEN ITERATE
  FC = LISTDSI(dsname)
  IF SYSDSORG ¬= 'PO' THEN ITERATE
  SAY 'Okay: ' dsname 'is ' SYSDSORG
  LEAVE
END