OPEN (QSAM)

Syntax:

OPEN('QSAM',ddname[,option])

Arguments:

'QSAM'

indicates that the QSAM access method is to be used to open the file. This argument must be coded as shown.

ddname

is the 1 to 8 character name that identifies the data set you want to process. This name needs to have been previously associated with the data set, either via the ALLOCATE command or JCL DD statement. If you try to open a ddname that is already open, the request is ignored and no error indication is given.

Note: The names 'VSAM', 'QSAM', and 'BPAM' are reserved. Do not use these strings for ddnames.

option

one of the following values may be used:

'INPUT': indicates that records will be read, only. This is the default.
'OUTPUT': indicates that records will be written, only.
'UPDATE': indicates that records will be read, and that some or all records may be re-written.

Module Name:

SWXOPEN

Service Description:

OPEN is used to "connect" your program to a data set. You must open a data set before you can get (using the GET function) records from the data set, or put (using the PUT function) records into the data set. All data sets should be closed (using the CLOSE function) when you are finished using them.

Note: The Shadow REXXTOOLS QSAM interface is in no way connected with the REXX EXECIO command.

Returned Information:

The OPEN function returns the QSAM OPEN macro return code. If you CALL the OPEN function, the returned value is contained in the RESULT special variable.

After completion of an OPEN function call, the RC and REASON variables will contain return code information. Several other variables are also produced. You should treat these variables as "read only" and make no attempt to modify any of them. The variables are:

RC: Contains the QSAM OPEN return code. An RC of zero means the operation was completed successfully.
REASON: Contains the QSAM OPEN reason code.
$SWXRECFM: Indicates the record format of the data set.
$SWXLRECL: Specifies the maximum record length of records in the opened data set.
$SWXBLKSI: Specifies the maximum length of a block for the data set.
$SWXBUFNO: Specifies the number of BLKSIZE-sized buffers that will be used in performing input/output operations.

Examples:

Allocate and open a sequential file for read access:
```
"alloc fi(indd) da(user.data) shr reu"
if open('qsam','indd') <> 0 then say 'Open failed.'
```
Note that no option is specified because 'INPUT' is the default.

Allocate and open a PDS member for update access:

"alloc fi(iodd) da(mypds.data(stuff)) shr reu"
call open 'qsam', 'iodd', 'update'
if rc <> 0 then say 'Open failed.  REASON='reason