Mainframe, MVS and zOS Discussion

Hi,

Could anyone clearly explain me the difference between UNIT and VOL Parameter in JCL? Are not they just same?

Unit and volume specify the location of a dataset.Unit specifies whether the dataset resides in DASD or TAPE
so you mention

UNIT=SYSDA or UNIT=TAPE

VOL specifies the volume seial number

Also here a very good link about the relationship

http://pic.dhe.ibm.com/infocenter/zos/v ... 560114.htm

UNIT defines the type of device. VOL defines the actual tape or disk; this is important when a site may have hundreds of disk volumes and many thousands (even hundreds of thousands) of tape volumes. They are definitely NOT the same -- nowhere near it.

Thanks Pandora.

Thanks Robert - your reply is pretty helpful to understand this. Many thanks.

Glad it helped :-)