Dynamic allocation of new data sets

FTP enables you to dynamically allocate a new physical-sequential data set, partitioned data set (PDS), or partitioned data set extended (PDSE) for the purpose of transferring data to be written to that data set. The following optional allocation variables can be used by the client to override and turn off the hard-coded defaults that affect the allocation of the data set.

Variable	FTP.DATA parameter
allocation units	SPACETYPE
blocksize	BLKSIZE
data class	DATACLASS
directory blocks	DIRECTORY
data set name type	DSNTYPE
extended attributes	EATTR
logical record length	LRECL
management class	MGMTCLASS
model DCB values	DCBDSN
PDS type	PDSTYPE
primary space	PRIMARY
record format	RECFM
retention period	RETPD
secondary space	SECONDARY
storage class	STORCLASS
unit	UNITNAME
volume count	VCOUNT
unit count	UCOUNT
volume serial number	VOLUME

The MVSGet and MVSPut subcommands affect the values that are configured with the PDSTYPE, DIRECTORY, DSNTYPE, RECFM BLKSIZE, LRECL, PRIMARY, SECONDARY, EATTR and SPACETYPE parameters. The subcommands reset these configured values to match the attributes of the source data set in the same way as if you had configured the values with the SITE or LOCSITE subcommand.

Some of these allocation variables might provide duplicate information. For example, the model DCB might have a record format (RECfm) that differs from the record format specified by a data class and from the one explicitly specified by the client. FTP passes all variables that are specified to dynamic allocation and lets it determine which of the specifications takes precedence. The following list describes the exceptions to that policy:

If neither the primary nor secondary space quantity is specified, the allocation units value is not sent.
If the data set organization is physical-sequential, directory blocks specification is not sent.
If the data set organization is PO (PDS or PDSE), the data set name type specification is not sent.
Otherwise, all variables are sent to dynamic allocation where the order of precedence is:
1. Any attributes set by the MVSGet or MVSPut subcommand
2. Any FTP.DATA, SITE, or LOCSITE configuration options explicitly specified or defaulted
3. Any attributes picked up from the model DCB and not otherwise explicitly specified
4. Any attributes picked up from the data class and not previously derived from 1 or 2
5. Any allocation defaults