I — data set information

If you select option I, the location, characteristics, and current space utilization of the specified data set are displayed. The format ISPF uses to display data set information when DFSMSdfp is not installed or is not available, or when the Storage Management Subsystem is not active, is shown in U — uncatalog data set. See Information for managed data sets to see how ISPF displays data set information when these products are installed, available, and active.

For sequential data sets, options I and S display the same information. For multivolume data sets, options I and S display current allocation and utilization values that represent totals from all volumes used. You may not enter a volume serial when you are requesting information on a multivolume data set.

Note:

The space for data sets allocated in blocks is calculated as if all of the tracks, including the last one, contain only full blocks of data. Any partial "short" blocks are ignored.
The information shown for current space utilization is the actual data that the data set contains, based on the number of allocation units (blocks, tracks, bytes, megabytes, and so on) that have been written. For a data set allocated in units other than tracks and cylinders, it does not include the unused portion of a track that is only partially filled.
For example, if a data set allocated in bytes with block size of 600 has one block written to a device with a track size of 1000, 600 bytes of data are written and the remaining 400 bytes cannot be used by a different data set. A track is the smallest possible unit of physical allocation to a data set on DASD. ISPF reports 600 bytes used while other products (such as ISMF) report 1000 bytes used. ISPF reports the space occupied by data in the data set. ISMF reports the space used by this data set that is not available for use by another data set. The difference is a relative indication of the effectiveness of the block size used when the data set was created.

Figure 1. Data Set Information panel (ISRUAIP)

                              Data Set Information

 Data Set Name . . . . : MYPROJ.DEV.SOURCE

 General Data                          Current Allocation
  Management class . . : STANDARD       Allocated cylinders : 1
  Storage class  . . . : BASE           Allocated extents . : 1
   Volume serial . . . : MVS8WF         Maximum dir. blocks : 20
   Device type . . . . : 3390
  Data class . . . . . : **None**
   Organization  . . . : PO            Current Utilization
   Record format . . . : FB             Used cylinders  . . : 1
   Record length . . . : 80             Used extents  . . . : 1
   Block size  . . . . : 27920          Used dir. blocks  . : 1
   1st extent cylinders: 1              Number of members . : 1
   Secondary cylinders : 1
   Data set name type  : PDS

   Creation date . . . : 2002/07/08     Referenced date . . : 2002/07/23
   Expiration date . . : ***None***

 Command ===>                                                                 
  F1=Help      F2=Split     F3=Exit      F7=Backward  F8=Forward   F9=Swap
 F12=Cancel

If the volume serial is followed by a plus (for example, HSM016+), the data set spans multiple volumes. Press Enter to display a list of all allocated volumes that have been used, as shown in Figure 2.

Figure 2. Volume Information for a Multivolume Data Set (ISRUAMVI)

This screen dump shows the Data Set Information panel with the Volume Information pop-up that shows the number and name of the allocated volumes.

The "Allocated units" and "Used units" fields can vary, depending on the value that was specified in the "Space units" field when you allocated the data set. For example, Figure 2 shows what the Data Set Information panel would look like if the data set was allocated by specifying Cylinders in the "Space units" field.

If directory block information is not available, the Data Set Information panel shows a value of 0 * for the "Maximum dir. blocks", "Used dir. blocks", and "Number of members" fields. The asterisk beside the zero refers you to a note on the panel, which states that the directory is unavailable.

If the data set is a PDS, ISPF must open it to retrieve the directory information. This updates the referenced date for the next time option I is displayed.

If the data set is a PDSE, the "Data set name type" field is LIBRARY and the "Maximum dir. blocks" field is NOLIMIT. Because the used blocks, used extents, and used directory blocks are not applicable to a PDSE, the Data Set Information panel replaces these values with "Used pages" and "% Utilized" (Figure 3). Other values that can appear in the "Data set name type" field are:

HFS - MVS™ Hierarchical File System data set
EXTENDED - DFSMSdfp Striped data set
LARGE - Large format sequential data set

Note: When a PDSE data set is created, it sets aside five pages. This may cause a significant change to the "% Utilized" value for a small data set.

Figure 3. Data Set Information for PDSE Managed Data Sets (ISRUAISE)

This screen dump shows Data Set Information.