BLSG Dialog Program - Activate IPCS Dialog Services

Invoke the BLSG dialog program through one of the following methods:

Use ISPEXEC with the ISPF SELECT service. From ISPF, enter:
```
ISPEXEC SELECT PGM(BLSG) PARM(PANEL(BLSPPRIM)) NEWAPPL(BLSG) PASSLIB
```
Using Alternate Panels: You can use panels other than BLSPPRIM as the entry to the IPCS dialog, and you can use command and program logic to determine which panel to display at the time the dialog is activated. To specify an alternate panel, replace PANEL(BLSPPRIM) with another value that the ISPF SELECT service accepts, as shown in the following examples:
Example 1: Specify that ISPF is to display an installation-written panel called PANLIPCS instead of BLSPPRIM as the initial panel of the IPCS dialog.
```
ISPEXEC SELECT PGM(BLSG) PARM(PANEL(PANLIPCS)) NEWAPPL(BLSG) PASSLIB
```
Example 2: Specify that ISPF is to process an installation-written command called CMDIPCS that determines which panel is displayed as the initial panel of the IPCS dialog.
```
ISPEXEC SELECT PGM(BLSG) PARM(CMD(CMDIPCS)) NEWAPPL(BLSG) PASSLIB
```
This option might be useful if IPCS users at the installation specialize in different areas, and you want to provide panels tailored to the specific needs of each area. This command can be implemented using a CLIST or REXX exec, or as an unauthorized TSO/E command.
Example 3: Specify that ISPF is to process an installation-written dialog program called PGMIPCS that displays installation-developed dialog panels.
```
ISPEXEC SELECT PGM(BLSG) PARM(PGM(PGMIPCS)) NEWAPPL(BLSG) PASSLIB
```
Alternate Panels and Performance: If you are using alternate panels to create a customized dialog, keep in mind that the point at which you invoke BLSG can affect performance. While BLSG is active, it serves as the owner of data sets used to support ISPF logical screens. BLSG closes these data sets when the SELECT service returns control to BLSG and BLSG ends. You can structure the dialog using either of the following methods:
- Invoke BLSG before displaying the primary option panel
- Display the primary option panel first, and then invoke BLSG when the user requests a specific IPCS function from the primary option panel.
The first method is more efficient, in that IPCS releases the resources it has accumulated only when the user exits the IPCS dialog. With the second method, IPCS releases resources after each request completes. Thus, with the second method, response time is longer when the user requests different functions, because IPCS must prepare and release resources as part of each request. You might want to use the second method, however, if other services that you want to provide during the ISPF session will not operate effectively while IPCS holds resources.
Use the ISPSTART command. From TSO/E READY or from IPCS line mode, enter:
```
ISPSTART PGM(BLSG) NEWAPPL(BLSG) PASSLIB PARM(PANEL(BLSPPRIM))
```
Add an option to an ISPF panel that users can select to start the IPCS dialog. The line to add to the processing section of the panel is:
```
I,'PGM(BLSG) PARM(PANEL(BLSPPRIM)) NEWAPPL(BLSG) PASSLIB'
```

Note: Specify PASSLIB only if both of the following are true:

You also specify NEWAPPL(BLSG).
You are running ISPF Version 2 Release 2 or later.