Exit 16: log, list, trace, and temporary data set allocation exit

This user exit lets you maintain your own data set naming conventions. ISPF calls the routines at this user exit before allocating the log, list, or temporary control data sets. As a result, you can provide a prefix for the name of the data set to be allocated. However, if the data set has been preallocated, ISPF does not use this prefix.

The exit routine can provide a prefix up to 26 characters long. A zero length prefix is flagged as an error. ISPF reserves the remaining 18 characters of the data set name for its own use.

ISPF builds the names of the log, list, and temporary control data sets according to these rules:

If a data set prefix is specified in the TSO user profile table (UPT) and it is different from the user ID, the data set name is of the form:
- uptpfx.userid.ISPF-specific-suffix
If a prefix is not specified in the UPT or if it is the same as the TSO user ID, the data set name is:
- userid.ISPF-specific-suffix
If a user ID is not available (executing ISPF in BATCH), ISPF recommends that the TSO PROFILE command be used to place the user ID in the UPT prefix field. In that case, the data set name has the this form:
- uptpfx.ISPF-specific-suffix
Note that UPTPFX is assumed to be the user ID in this case.

If you provide an exit routine at this user exit, ISPF allows the data set names to be of the form:

Exit-provided-prefix.ISPF-specific-suffix

The 18 characters reserved by ISPF begin with the period separator.

Because the user ID is also passed to the exit routine as part of the prefix, the exit routine is responsible for maintaining unique data set names.

Exit parameters

In addition to the standard exit parameters described in Exit parameter list, the exit routines at this user exit receive these parameters.

prefix-len

A fullword binary number that identifies the length of the prefix field. On entry to the exit routine, it is the length of the prefix including the UPT prefix, the user ID or both. On return to ISPF, it should contain the length of the prefix provided by the exit routine.

The value of this parameter must be in the range 1 to 26, inclusive.

prefix

A 26-character field that contains the data set name prefix used by ISPF. On entry to the exit routine, it contains the UPT prefix, the user ID, or both left-justified within the field.

On return to ISPF, it can contain any prefix (up to 26 characters) chosen by the exit. ISPF does not do any validity checking of the specified prefix. This prefix must be left-justified. If an incorrect prefix is provided, allocation of the data set fails.

suffix-type

A fullword of bit flags indicating the type of data set that ISPF allocates:

0: 1 = List data set
1: 1 = Log data set
2: 1 = Temporary listing data set
3: 1 = Temporary control data set
4: 1 = Temporary work data set
5: 1 = ISPVCALL trace data set
6: 1 = ISPDPTRC trace data set
7: 1 = ISPFTTRC trace data set
8-31: Reserved.

suffix-len

A fullword binary number containing the length of the value within the suffix field. ISPF ignores any changes the exit routine makes to this field.

suffix

An 18-character field containing the name of the data set name suffix that ISPF uses. ISPF ignores any changes the exit routine makes to this field.

Return codes

No return codes are acknowledged. Upon return to ISPF, the data set name is generated using the prefix provided by the exit routine (if any) and normal processing continues.

Note: For multiple exit routines, return codes still affect the processing flow.