Rational Developer for System z
Enterprise PL/I for z/OS, Version 3.8, Programming Guide

Essential information for creating and accessing regional data sets

To create a regional data set, you must give the operating system certain information, either in your PL/I program or in the DD statement that defines the data set. The following paragraphs indicate the essential information, and discuss some of the optional information you can supply.

You must supply the following information when creating a regional data set:

If you want to keep a data set (that is, you do not want the operating system to delete it at the end of your job), the DD statement must name the data set and indicate how it is to be disposed of (DSNAME and DISP parameters). The DISP parameter alone will suffice if you want to use the data set in a later step but do not need it after the end of your job.

If you want your data set stored on a particular direct access device, you must indicate the volume serial number in the DD statement (SER or REF subparameter of VOLUME parameter). If you do not supply a serial number for a data set that you want to keep, the operating system allocates one, informs the operator, and prints the number on your program listing. All the essential parameters required in a DD statement for the creation of a regional data set are summarized in Table 22; and Table 23 lists the DCB subparameters needed. See your z/OS JCL User's Guide for a description of the DCB subparameters.

You cannot place a regional data set on a system output (SYSOUT) device.

In the DCB parameter, if you specify the DSORG parameter, you must specify the data set organization as direct by coding DSORG=DA. You cannot specify the DUMMY or DSN=NULLFILE parameters in a DD statement for a regional data set. Using DSORG=DA may cause message IEC225I to be issued. This message can be safely ignored.

Table 22. Creating a regional data set: essential parameters of the DD statement
Parameters
What you must state
When required
UNIT= or
VOLUME=REF=
 
SPACE=
 
DCB=
Output device1
 
 
Storage space required2
 
Data control block information:
see Table 23
Always
DISP=
Disposition
Data set to be used in another job step but not required in another job
DISP=
 
DSNAME=
Disposition
 
Name of data set
Data set to be kept after end of job
VOLUME=SER= or
VOLUME=REF=
Volume serial number
Data set to be on particular volume

1Regional data sets are confined to direct access devices.

2For sequential access, the data set can have up to 15 extents, which can be on more than one volume. For creation with DIRECT access, the data set can have only one extent.

To access a regional data set, you must identify it to the operating system in a DD statement. The following paragraphs indicate the minimum information you must include in the DD statement; this information is summarized in Table 24.

If the data set is cataloged, you need to supply only the following information in your DD statement:

If the data set is not cataloged, you must, in addition, specify the device that will read the data set and give the serial number of the volume that contains the data set (UNIT and VOLUME parameters).

When opening a multiple-volume regional data set for sequential update, the ENDFILE condition is raised at the end of the first volume.

Table 23. DCB subparameters for a regional data set
Subparameters
To specify
When required
RECFM=F
 
BLKSIZE=
 
DSORG=DA
Record format1
 
Block size1
 
Data set organization
These are always required

1Or you can specify the block size in the ENVIRONMENT attribute.

Table 24. Accessing a regional data set: essential parameters of the DD statement
Parameters
What you must state
When required
DSNAME=
 
DISP=
Name of data set
 
Disposition of data set
Always
UNIT= or
VOLUME=REF=
 
VOLUME=SER=
Input device
 
 
Volume serial number
If data set not cataloged

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