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 Windows or UNIX
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 MSS but have no meaning in a PC or UNIX environment.

The following table shows the record formats for VSAM files.

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

Notes:

A cataloged VSAM file has two extra properties, LRECL Avg (average record length) and LRECL Max (maximum record length). If these two properties have the same value, MSS assumes that the file has fixed length records and does not use record delimiters to separate the records on Windows or UNIX.. If they have different values, MSS assumes that the record has variable length records and uses the Micro Focus type delimiters to separate records on Windows or UNIX.
If you have a program compiled to use EBCDIC, but that program reads a file with a RECFM of LSEQ and a character set of ASCII, the file's data is automatically converted to EBCDIC as part of the read. This automatic conversion is useful when reading files that do not contain hexadecimal data, such as control cards.
You allocate VSAM data sets to the MSS catalog using New on the ESMAC catalog page, or by submitting a batch job to define the file using IDCAMS.
If your application uses record-level locking on shared VSAM files, you might find that files larger than 1 GB (gigabyte) cannot be accessed. This is because the default record locking mechanism in MSS uses the top two bits of the file address for locking and compression bits, thus reducing the address space for the maximum offset from 4 GB to 1 GB for a shared idxformat 3 or 4 file. If you encounter this problem, set the LOCKTYPE Compiler directive to 2 when you compile the program affected. With this setting, the file handling mechanism creates a separate file for storing record locks, with the same basename as the file and a .lck extension.