Opening a file

The OPENFILE statement has the following syntax:

OPENFILE filename  {INPUT }  /* to read records from the file
                   {OUTPUT}  /* to write records to the file
                   {UPDATE}  /* to update records in the file

To open a data set for I/O, you must allocate the data set to a file name, then use that file name on the OPENFILE statement. To preserve data integrity, after the file is opened for I/O, CLIST performs only one level of substitution against the file name variable. That is, after the file name is substituted with a file record, and to ensure the file record can be saved in its original format, CLIST does not re-scan the record.

To allocate the data set to a file name, use the ALLOCATE command with the FILE keyword. The file name is an arbitrary value; you can create it on the allocation.

For example, you can code the following:

⋮
allocate file(paycheks) da('d58tan1.checks.data') shr
OPENFILE PAYCHEKS
⋮

You can also code the file name as a symbolic variable as follows:

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SET FILEID= PAYCHEKS
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allocate file(&FILEID) da('d58tan1.checks.data') shr
OPENFILE &FILEID
⋮

You can open a member of a PDS after allocating the member to a file name, for example:

allocate file(income) da('d58tan1.receipts(july)') shr
OPENFILE INCOME

However, do not use OPENFILE statements to open more than one member of a PDS for output at the same time.