How to access a variable length record from varible block fi

gokuldass · New User Joined: 18 Mar 2005 Posts: 48 Location: india

Hello Guys,

How to access a variable length record from varible block file? What are the changes that I need to do on the DCB parameter to access a variable length file..

Also, how to define the assembler variable for varible length record.

Please let me know with a sample code & explaination.

Thanks in advance.

Regards,
Gokuldass

UmeySan · Posted: Mon Sep 18, 2006 5:17 pm

Hi !

Specify RECFM=VB in the DCB.
The normal GET will provide you the records you read.
When you want to write such records you have to provide the length field.

Definition of an area, in wich you read the record is done in normal way.
Must be max-size, the records can have.

Regards, UmeySan

TizMe · New User Joined: 05 Jan 2006 Posts: 72

Don't forget to clear your data area before loading your input record to ensure that you don't get residual data from a previous longer record.

UmeySan · Posted: Tue Sep 26, 2006 2:04 pm

Hi TizMe !

That's correct. But what's about the VarLength? And what is, if Lrecl is grater 255Bytes?

According to your example, you also can do this by an XC instruction.
XC record,record ...set all bytes of record to hex-zero

I think, best way for variable cleaning is to use a MVCL instruction.

S3L00 DS 0H Delete the InOutSentence

L R4,AS3SATZ ...Adress of Sentence
L R5,=A(30000) ...Max Length
*
LA R2,S3LHNULL ...Init Field Hex Zero
SR R3,R3 ...Clean Register 3
ICM R3,8,=X'00' ...DeleteCharacter is Hex Zero
*
MVCL R4,R2 ...Clear the whole Sentence 30.000 Bytes

In stead of "L R5,=A(30000)" you could load the actual length of the actual record into register 5. Use the LengthBytes of the record.

Regards, UmeySan

UmeySan · Posted: Tue Sep 26, 2006 2:11 pm

Hi TizMe !

I forgot something, sorry.

In your example, you have to take care of the fields defined after DATA.
MVI DATA,C' '
MVC DATA+1(length),DATA

Here length has to be "LengthOfData - 1Byte"
MVC DATA+1(L'DATA-1),DATA

You also can define one Byte before the field called DATA for only use of cleaning an then using this field in your command. No use of length.
DC CL01' '
DATA DC CL80' '

MVC DATA,DATA-1

Regards, UmeySan