FREAD

FREAD numfile,string[,KEY=key,KEYLEN=key-length,

RECLEN=rec-length,UPDATE=NO]

Description

This statement read a record from the file numfile; string will contain this record and its length must be greater or equal than record length
numfile is a numeric constant (from 1 to 20) used in FOPEN statement to handle the file.
key is the variable containing the read-key if the file is a KSDS or a RRDS
key-length is the length of this key
rec-length is the maximum record length: if a record is greater, the value in string is truncated

Let's summarize now how to use this instruction:

For a VSAM file (MVS/TSO/DOS/CICS):

• for a direct access (fetch only one record) specify only KEY= (without KEYLEN=); KEY is a string variable for a KSDS, an integer meaning slot number for a RRDS and an integer meaning a record-RBA for a ESDS (if you know the correct RBA)
• for a start browse (fetch for a partial key or full key) specify both KEY= and KEYLEN= and then fetch next records using a sequential read without KEY; you can use FSTARTBR statement to do the same thing, but STARTBR don't actually read any record
• for a sequential access don't use any KEY parameter
• use UPDATE=YES if the read record should be updated or deleted in the next

For a sequential (SAM) file (MVS/TSO/DOS):

• for a sequential access (the only allowed access method) don't use any KEY parameter

For a CMS file (CMS):

• for a sequential access don't use any KEY parameter and the read is from the first record
• for a direct access (fetch only one record) specify KEY= ; KEY is a integer variable containing the record number; use FSTARTBR statement to do a Start Browse access on a CMS file

RECLEN= is an optional parameter that simply overrides the length of string.

The only Return code filled in every environment are $EOF (End Of File, that can be 'F' false or 'T' true) and $RCFILE; $RCVSAM is filled only managing VSAM files.

 

Parameter specifications

	Parameter Name	Mode	Type	coding	Remark
1	numfile	Input	numeric	constant	from 1 to 20
2	string	Output	String	C or X	Read record
	KEY=	Input	String	C or X	If file is a KSDS
	KEY=	Input	Integer	F	If file is a RRDS or a CMS file
	KEYLEN=	Input	Integer	F or H	for a partial key
	RECLEN=	Input	Integer	F or H or const.	overrides the length of string
	UPDATE=NO/YES	fixed	string		YES only for a following FDELETE