Implementing the ISPF Dialog Interface › Manage Temporary Data Sets

Manage Temporary Data Sets

Dialog procedures are designed to eliminate temporary data sets, allocated for staged file transmissions, as soon as the request is complete. However, various errors are possible (such as link failure), which result in such data sets not being deleted by the usual system processes.

Since every user of the ISPF dialog is not aware of the various mechanisms involved in scheduling the transmission, it is assumed that the installation needs to perform some regular housekeeping procedures to delete any unwanted data sets.

This requires knowledge of the names allocated to temporary data sets. The installation has some control over these names by setting the variables &LCLPREF and &REMPREF through procedure NMFTSID. This prefix is used to construct the temporary data set names used by the dialog in the following manner.

The following staging data set name is used in the sending system:

&LCLPREF.&FTSNM.NMSTGO

The following staging data set name is used in the receiving system:

&REMPREF.&FTSNM.NMSTGI

The following IEBCOPY control file name is allocated in the sending system:

&LCLPREF.&SYSUID.SYSIN

The variable &SYSUID is the TSO user ID of the person using the dialog and is a standard dialog system variable. The variable &FTSNM is the TSO user ID (&SYSUID) plus one character (A to Z), which is the transmission name constructed by the dialog to uniquely identify this request.

Only one IEBCOPY control file is required and is deleted after the output staging data set is created. The staging data set names are tied to the transmission request names for ease of reconstructing at the receiving end and also as a convenient means to make the name unique.

Depending upon the exact nature of the staged transmission, particular NCL procedures are invoked upon its successful completion in both the sending and receiving systems. In the sending system, the procedure $@DELETE is always invoked and the value of &LCLPREF, defined by the installation as the local staging data set prefix, is passed as a parameter to this procedure. It deletes the staging data set on the local system and notifies the TSO user of the successful transmission. In the receiving system, the prefix cannot be carried as a parameter and must be determined by calling the NCL procedure $@NMFTS. When determining what values to use for the &REMPREF variable defined in the dialog procedure NMFTSID, remember that procedure $@NMFTS, executing in the remote system, must be able to reconstruct such a prefix given only the original TSO user ID of the requestor. It returns this value in &PREFIX to the calling NCL procedure ($@COPY, $@REPRO, or $@E), which then constructs the entire staging data set name from which to reload the target data set and then delete.