Advanced Data Set Information

This chapter expands on the information presented in the chapter Files and Data Sets in your User's Guide. It covers the following subjects:

4.1 Data Set Organizations

The data set organizations supported by Mainframe Express are shown in the following table.

Abbreviation	Organization	Comment
DA	Direct access
DAU	Direct access, unmoveable
GDG	Generation data group
IS	Indexed sequential
ISU	Indexed sequential, unmoveable
PDSM	Partitioned data set member	Micro Focus organization
PO	Partitioned
POU	Partitioned, unmoveable
PS	Physical sequential
PSU	Physical sequential, unmoveable
VSAM	Virtual storage access method

4.2 Record Formats

The following table shows the record formats for all the data set organizations except VSAM.

Abbreviation	Format	Control Characters	Record Delimiters	Comment
F	Fixed	None	None
FA	Fixed	ANSI	None
FB	Fixed blocked	None	None	Same as F format
FBA	Fixed blocked	ANSI	None	Same as FA format
FBM	Fixed blocked	Machine	None	Same as FM format
FBS	Fixed blocked spanned	None	None	Same as F format
FM	Fixed	Machine	None
FS	Fixed spanned	None	None	Same as F format
LSEQ	Line sequential	None	Carriage return/line feed
U	Undefined			Results unpredictable on PC
V	Variable	None	Micro Focus type
VA	Variable	ANSI	Micro Focus type
VB	Variable blocked	None	Micro Focus type	Same as V format
VBA	Variable blocked	ANSI	Micro Focus type	Same as VA format
VBM	Variable blocked	Machine	Micro Focus type	Same as VM format
VBS	Variable blocked spanned	None	Micro Focus type	Same as V format
VM	Variable	Machine	Micro Focus type
VS	Variable spanned	None	Micro Focus type	Same as V format

Note: Blocked and spanned record formats are accepted by Mainframe Express but have no meaning in a PC environment.

Abbreviation	Format	Control Characters	Comment
ES	Entry sequence	None
KS	Key sequence	None
LS	Linear sequence	None	Not supported
RR	Relative record	None

4.3 Logical Record Length

Mainframe Express works with logical record lengths as defined in the following table:

Record Format	Logical Record Length
Fixed	Actual record length
Variable	Actual record length + 4
LSEQ	Maximum record length

4.4 Mapping to PC File Formats

Mainframe Express writes data sets to PC files using the following organization and record format mapping:

Mainframe	PC
Dataset Organization	Record Format	File Organization	Record Format	Comment
DA, DAU, PS, PSU	Any fixed (Fnn) or variable (Vnn) format	Sequential	Micro Focus
DA, DAU, PS, PSU	LSEQ	Line sequential	Micro Focus	Always uses ANSI character set. Can only be edited with a text editor
GDG				Catalog entry only
IS, ISU	Any fixed (Fnn) or variable (Vnn) format	Indexed sequential	Micro Focus
PDSM	Any fixed (Fnn) or variable (Vnn) format	Sequential	Micro Focus
PDSM	LSEQ	Line sequential	Micro Focus
PO, POU				Catalog entry only
VSAM	ES	Sequential	ESDS
VSAM	ES	Indexed sequential	ESDS	Alternate index defined
VSAM	KS	Indexed sequential	Micro Focus
VSAM	LS	Not supported
VSAM	RR	Relative	Micro Focus

4.5 Dynamic PDS Member Lists

Dynamic PDS member lists enable you to specify a PC-based directory that is to represent the contents of a mainframe-hosted PDS. When you define a PDS using a dynamic member list, you use the Dynamic PDS tab of the Allocate Dataset dialog box to specify a directory and list of extensions; Mainframe Express scans the specified directory for files with extensions matching those in the extension list, then dynamically builds the PDS's member list using the files it finds.

Although you can use a single directory to represent the contents of more than one PDS by using different extensions for the PDS members, we strongly recommend that you do not use this approach, as it could lead to conflicting member names if , for example, the extensions are changed to a wildcard, or if more than one extension is used per dynamic PDS.

We recommend that you do not use a directory associated with a dynamic PDS model with any other PDS models (regardless of whether they are dynamic or not). Although member list processing works successfully in such a scenario, behavior could be unexpected when editing a member by double-clicking on it from the Catalog View if the two models had differing DCB information.

When adding a file into a dynamic PDS, you must ensure that the new file is in the same directory as the directory specified when the dynamic PDS was created.

When allocating a new PDS member, the extension used for the new member is the first extension specified in the extension list.

When deleting a PDS member in a dynamic PDS, you must check Also delete associated data file(s) before clicking OK on the Delete Catalog Entries dialog box for the deletion to be carried out fully.

4.6 Support for mfextmap.dat and PROXMVS Files

Mainframe Express provides support for PROXMVS files as well as mfextmap.dat files created when using COBOL Workbench, where PROXMVS and COBOL Workbench are earlier products from Micro Focus. For information on how to use such files, see the chapters Migrating from PROXMVS and Your Mfextmap File in your Migration Cookbook.

4.7 Support for Generation Data Groups

A generation data group (GDG) consists of two parts: a GDG model and a series of physical sequential (PS) data sets, called biases (also known as generation data sets) that are associated with the GDG.

The following example illustrates a job that can be used to create a generation data group. STEP00 creates the GDG model and STEP01 creates five new GDG biases.

//MFIDMFGD JOB 'MFIDMFGD',CLASS=A,MSGCLASS=A,NOTIFY=MFIDF
//STEP00 EXEC PGM=IDCAMS
//SYSOUT DD SYSOUT=*
//SYSPRINT DD SYSOUT=*
//AMSDUMP DD SYSOUT=*
//SYSIN DD *
DELETE MFIDMF.TEST.GDG
DEFINE GENERATIONDATAGROUP
(NAME(MFIDMF.TEST.GDG) EMPTY NOSCRATCH LIMIT(96))
/*
//STEP01 EXEC PGM=IEFBR14
//SYSUXX DD
      DSN=MFIDMF.TEST.GDG(+1),DISP=(NEW,CATLG),SPACE=(TRK,(5,2))
//SYSUXY DD
      DSN=MFIDMF.TEST.GDG(+2),DISP=(NEW,CATLG),SPACE=(TRK,(5,2))
//SYSUXZ DD
      DSN=MFIDMF.TEST.GDG(+3),DISP=(NEW,CATLG),SPACE=(TRK,(5,2))
//SYSUXA DD
      DSN=MFIDMF.TEST.GDG(+4),DISP=(NEW,CATLG),SPACE=(TRK,(5,2))
//SYSUXB DD
      DSN=MFIDMF.TEST.GDG(+5),DISP=(NEW,CATLG),SPACE=(TRK,(5,2))

Five biases named MFIDMF.TEST.GDG.G0001V00, MFIDMF.TEST.GDG.G0002V00, MFIDMF.TEST.GDG.G0003V00, MFIDMF.TEST.GDG.G0004V00 and MFIDMF.TEST.GDG.G0005V00 are created by STEP01.

A bias can be processed by its relative number, its actual reference or as a part of the entire generation data group. For example, each of the following statements could be executed after running the previous job.

This would cause the entire generation data group MFIDMF.TEST.GDG, consisting of a set of concatenated data sets MFIDMF.TEST.GDG.G0001V00 through MFIDMF.TEST.GDG.G0005V00, to be referenced.

The relative number 0 would cause the data set named MFIDMF.TEST.GDG.G0005V00 to be referenced.

The relative number -1 would cause the data set named MFIDMF.TEST.GDG.G0004V00 to be referenced.

The relative number +1 would cause a new data set named MFIDMF.TEST.GDG.G0006V00 to be referenced.

The actual reference G0003V00 would cause the data set named MFIDMF.TEST.GDG.G0003V00 to be referenced.

The increment of numbers occurs per job, so if you had two consecutive steps that referenced +1, then each step would be using the same data set.

4.7.1 Generation Data Group Restrictions