CRTDDMF (Create DDM File) considerations

For applications running on an iSeries™ server to access remote files, the programmer must use the CRTDDMF command to create an object called a DDM file.

The ACCMTH parameter of this command shows which DDM access method should be used when opening the remote file. If *RMTFILE is used, i5/OS™ DDM selects an access method that is compatible with:

The type of VSAM data set being accessed
The access methods supported by CICS/DDM for the VSAM data set

The table below shows how the possible values for the ACCMTH parameter correspond to VSAM data sets.

Table 1. ACCMTH parameter of iSeries CRTDDMF command
ACCMTH parameter values	VSAM data set organization
ACCMTH parameter values	ESDS	RRDS	KSDS	VSAM Path
*ARRIVAL	R	R	E	E
*KEYED	E	E	R	R
*BOTH	E	O	O	O
*RANDOM	E	O	O	O
*SEQUENTIAL	R	O	O	O
*COMBINED	E	O	E	E
Where: R Shows the parameter is required for accessing the VSAM data set. O Shows the parameter is optional for accessing the VSAM data set. E Shows the parameter causes an i5/OS message.

To improve performance, the iSeries user might want to supply values other than *RMTFILE for the ACCMTH parameter. To avoid server messages, use the values specified in Table 1 when accessing remote VSAM data sets.

The value specified for the RMTFILE file parameter must be the same as the value specified for the DATASET parameter of the CICS^® DFHFCT macro when the VSAM data set is defined to the CICS system.