my %dispatch = (
# Key = name of proc
# Value = array of arguments to pass
    "PAR_REPORTS_POS.SUN_PRC_AT_I_POSM1D007" =>
        [ \$retcode, \$retmsg ],
    "PAR_REPORTS_POS.SUN_PRC_AT_I_POSM1W001" =>
        [ \$retcode, \$retmsg, \$finRepId, \$showPendingPolicies ],
# and so on
);
# Later...
my $args = $dispatch{$procName};
my $procedure =
    "BEGIN $procName( "
    . join(',', (('?') x @$args))
    # that makes a comma-separated list of '?'s,
    # the same number as there are elements in $args
    . "); END;";
my $function = $dbh->prepare($procedure);
my $argc = 1;
for my $arg (@$args)
{
    $function->bind_param($argc++, $arg, SQL_VARCHAR);
}
$function->execute;

##</code><code>##

my ($procedure, $function);
DISPATCH: {
    if ($procName eq "PAR_REPORTS_POS.SUN_PRC_AT_I_POSM1D007")
    {
        $function = $dbh->prepare("BEGIN $procName(?, ?); END;");
        $function->bind_param(1, \$retcode, 100); #? 100?
        $function->bind_param(2, \$retmsg, 100);
        last DISPATCH;
    }
    if ($procName eq "PAR_REPORTS_POS.SUN_PRC_AT_I_POSM1W001")
    (
        $function = $dbh->prepare("BEGIN $procName(?, ?, ?, ?); END;");
        $function->bind_param(1, \$retcode, 100); #? 100?
        $function->bind_param(2, \$retmsg, 100);
        $function->bind_param(3, \$finRepId, SQL_VARCHAR);
        $function->bind_param(4, \$showPendingPolicies, SQL_VARCHAR);
        last DISPATCH;
    }
    # and so on...
} #close block labelled DISPATCH;
$function->execute;