//DD1  DD  DSNAME=&&TEMP,UNIT=MIXED,SPACE=(CYL,10)

The DD statement defines a temporary data set. The UNIT parameter requests any available tape or direct access volume; MIXED is the installation’s name for a group of tape and direct access devices. If a tape volume is assigned, the SPACE parameter is ignored; if a direct access volume is assigned, the SPACE parameter is used to allocate space to the data set. The SPACE parameter specifies only the required subparameters: the type of allocation and a primary quantity. It requests that the system allocate 10 cylinders.

//DD2  DD  DSNAME=PDS12,DISP=(,KEEP),UNIT=3390,
//         VOLUME=SER=25143,SPACE=(CYL,(10,,10),,CONTIG)

The DD statement defines a new partitioned data set. The system allocates 10 cylinders to the data set, of which ten 256-byte records are for a directory. Since the CONTIG subparameter is coded, the system allocates 10 contiguous cylinders on the volume.

//REQUEST1 DD  DSNAME=EXM,DISP=NEW,UNIT=3390,VOLUME=SER=606674,
//          SPACE=(1024,75),DCB=KEYLEN=8
//REQUESTA DD  DSNAME=EXQ,DISP=NEW,UNIT=3390,
//          SPACE=(1024,75),DCB=KEYLEN=8

These DD statements request space in block lengths. The average block length of the data is 1024 bytes. 75 blocks of data are expected as output. Each block is preceded by a key eight bytes long. The system computes how many tracks are needed, depending on the device requested in the UNIT parameter.

//REQUEST2 DD  DSNAME=PET,DISP=NEW,UNIT=3390,VOLUME=SER=606674,
//          SPACE=(ABSTR,(5,1))

In this example, the SPACE parameter asks the system to allocate 5 tracks, beginning on the second track of the volume.

//DD3    DD  DSNAME=MULTIVOL,UNIT=3390,DISP=(,CATLG),
//          VOLUME=SER=(223344,223345),SPACE=(CYL,(554,554))

This example shows how to create a multivolume data set on two complete volumes. The two volumes do not contain other data sets. A volume on 3350 Direct Access Storage contains 555 cylinders. The unrequested cylinder contains the volume table of contents (VTOC).

//SMSDS3  DD  DSNAME=MYDS3.PGM,DATACLAS=DCLAS03,DISP=(NEW,KEEP),
//          SPACE=(128,(5,2)),AVGREC=K

In this example, the space allocation defined in the DCLAS03 data class is overridden by the SPACE and AVGREC parameters, which indicate an average record length of 128 bytes, a primary quantity of 5K (5,120) records, and a secondary quantity of 2K (2,048) records.