Disable generic high-level qualifiers

ISPF allows a generic high-level qualifier when using option 3.4 to print or display a list of data set names. A generic high-level qualifier is one that contains a wildcard character. You can restrict the search limits (and improve performance) by disabling the use of wildcard characters in the first qualifier. You can do this in two ways:

Through the DISALLOW_WILDCARDS_IN_HLQ setting in the ISPF Configuration table.
By writing an exit that sets a return code to prevent the list from being generated when it finds a wildcard character. This method allows more flexibility, for example if you wish to allow a wildcard character at the end of a high-level qualifier but not at the start.

For more information about using the data set list filter exit, see Data set list filter exit.

Figure 1 is an example of a data set list exit that disables wildcards. A copy of this exit is included in your SISPSAMP data set in member ISRNOGEN. Note that this example as written is nonreentrant, so it should not be put in the LPA. If nonreentrant exits are put in the LPA, abends can occur.

Figure 1. Sample exit to disable generic high-level qualifiers (Part 1 of 2)

   TITLE ' ISRNOGEN:   PROC (PARM1,PARM2,PARM3,PARM4);'
* This program is an example of a data set list exit.  It checks
* for a generic high-level qualifier and sets the return code
* to prevent the list from being generated when there is a generic
* high-level qualifier.
ISRNOGEN CSECT ,
ISRNOGEN AMODE  31
ISRNOGEN RMODE  ANY
@PROLOG  STM   @14,@12,12(@13)
         BALR  @12,0
@PSTART  DS    0H
         USING @PSTART,@12
         MVC   PARMADDR(16),0(@01)
* If the first parameter is one, check the data set name for
* a generic character (% or *)
CHECK1   L     @04,PARMADDR
         CLC   PARM1(4,@04),ONE
         BNE   EXITRTN
* Check current Dsname
         L     @05,PARMADDR+4
         LR    @01,@05
         XR    @02,@02
* Translate and test for *, %, blank, or period
         TRT   DSNAME(44,@05),TABLE
         SR    @01,@05
         AR    @05,@01
* Check the character that stopped the translate and test for an
* asterisk or a percent sign.  If either of these is the first
* character found, the high-level qualifier is generic.
         CLC   DSNAME(1,@05),ASTERISK
         BE    ERROR
         CLC   DSNAME(1,@05),PERCENT
         BE    ERROR
* If the high-level qualifier is not an asterisk or percent sign,
* set the return code to allow the list to be displayed.
NAMEOK   SLR   @06,@06
         ST    @06,EXITRC
EXITRTN  DS    0H
         L     @15,EXITRC
         L     @14,12(,@13)
         LM    @00,@12,20(@13)
         BR    @14
* If the high-level qualifier is generic, set the return code to 8
* to prevent searching all catalogs.
ERROR    MVC   EXITRC(4),EIGHT
         B     EXITRTN
* Data for checkname                /*                               */
@DATA    DS    0H
         DS    0F
PARMADDR DS    4F
         DS    0F
ONE      DC    F'1'
TWO      DC    F'2'
FOUR     DC    F'4'
EIGHT    DC    F'8'
         DS    0D
EXITRC   DS    F
ASTERISK DC    C'*'
PERCENT  DC    C'%'

Figure 2. Sample exit to disable generic high-level qualifiers (Part 2 of 2)

* Translate and test table with blank, period, asterisk, and
* percent signs
TABLE    DC    64X'00'
         DC    X'40'
         DC    10X'00'
         DC    X'4B'
         DC    16X'00'
         DC    X'5C'
         DC    15X'00'
         DC    X'6C'
         DC    147X'00'
@00      EQU   00                      Equates for registers 0-15
@01      EQU   01
@02      EQU   02
@03      EQU   03
@04      EQU   04
@05      EQU   05
@06      EQU   06
@07      EQU   07
@08      EQU   08
@09      EQU   09
@10      EQU   10
@11      EQU   11
@12      EQU   12
@13      EQU   13
@14      EQU   14
@15      EQU   15
VOLUME   EQU   0
DSNAME   EQU   0
EXIT1    EQU   0
LEVEL    EQU   0
PARM1    EQU   0
PARM2    EQU   0
PARM3    EQU   0
PARM4    EQU   0
         DS    0D
@ENDDATA EQU   *
         END   ISRNOGEN