Variable Length Records on the Mainframe

On the mainframe, Variable length (VB) files are stored in the following format

Block Length
	Record Length	Data Line 1
	Record Length	Data Line 2
	...	...
	Record Length	Data Line n
Block Length
	Record Length	Data Line n+1
	Record Length	Data Line n+2
	...	...

When the file is transported to another system, the Block Length/Record Length is normally dropped leaving just the data. But you can copy a RECFM=VB file to a RECFM=U and then transport the RECFM=U file (with all the record lengths intact) to a PC/Unix system. The JCL to do this on the Mainframe:

// SET IN=VB.FILE.TO.TRANSMIT // SET OUT=USER.&IN..RECFMU //* //STEP010 EXEC PGM=IEFBR14,COND=(0,NE) //SORTOUT DD DSN=&OUT, // DISP=(MOD,DELETE), // SPACE=(TRK,(30,30),RLSE), // DCB=BLKSIZE=0 //* //STEP020 EXEC PGM=IEBGENER,COND=(0,NE) //SYSUT1 DD DSN=&IN,DISP=SHR,DCB=RECFM=U //SYSUT2 DD DSN=&OUT, // DISP=(NEW,CATLG), // SPACE=(TRK,(115,45),RLSE) //SYSPRINT DD SYSOUT=* //SYSOUT DD SYSOUT=* //SORTMSG DD SYSOUT=* //SYSIN DD DUMMY

Then to read it from java. Note: I am using

Constants.IO_VB_DUMP for the File Structure
Convert.FMT_MAINFRAME for the format



   9:            CobolIoProvider ioProvider = CobolIoProvider.getInstance();
  10:            AbstractLineReader reader  = ioProvider.getLineReader(
  11:                    Constants.IO_VB_DUMP, Convert.FMT_MAINFRAME,
  12:                    CopybookLoader.SPLIT_NONE, copybookName, vendorFile
  13:            );

   or

  19:           AbstractLineReader reader  = LineIOProvider.getInstance().getLineReader(Constants.IO_VB_DUMP);