Defining a C/I FSS address space

If you decide that establishing C/I FSS address spaces will help your installation, you must supply a cataloged procedure for starting the C/I FSS address spaces. Then, define each C/I FSS address space you want to establish using the FSSDEF initialization statement. (You cannot define or add a C/I FSS address space using operator commands.) Follow the steps given below.

Include a procedure for starting a C/I FSS address space in the appropriate procedure library for your installation. The default C/I FSS start procedure resides in SYS1.SIATSAMP in the members IATJ3CI and JES3CI. The JCL statements included in this procedure are:
```
//JES3CI  EXEC  PGM=IATINTKF,DPRTY=(15,14)
//STEPLIB   DD  DSN=SYS1.SIATLIB,DISP=SHR
//CHKPNT    DD  DSN=SYS1.JES3CKPT,DISP=SHR
//CHKPNT2   DD  DSN=SYS1.JES3CKP2,DISP=SHR
//JES3OUT   DD  SYSOUT=A
//JES3SNAP  DD  SYSOUT=A
//SYSABEND  DD  SYSOUT=A
//JESABEND  DD  SYSOUT=A
```
Using this default procedure as a guide, you can change the data set names and the SYSOUT classes to meet your installation's needs. Always specify the same checkpoint data set(s) as specified in the JES3 start procedure and share the data set(s).

In order to ensure an adequate region size, you may want to add a REGION= keyword to the EXEC JCL statement. The JES3CI procedure provided by IBM® does not include a REGION= keyword. Do not include JCL statements to define procedure libraries in the C/I FSS start procedure. If your JES3 load library is in the link list, you do not need the STEPLIB DD statement.
Include the appropriate FSSDEF statement(s) in your initialization stream, one for every C/I FSS address space you want to create.
- Specify TYPE=CI.
- The PNAME parameter should give the name of the cataloged procedure that starts C/I FSS address spaces, which is in the procedure library used for started tasks.
- Use the SYSTEM parameter to specify the JES3 processor on which you want to establish the C/I FSS address space.
- Use the START parameter to specify whether you want JES3 to automatically start this C/I FSS address space when an eligible processor is available and both subparameters of the DSPCNT parameter (see below) do not equal 0.
- Use the DSPCNT parameter to specify the maximum number of CI DSPs that may operate in the C/I FSS address space. Specify this number by giving the maximum number of DSPs for batch jobs or the maximum number of DSPs for demand select jobs that may operate concurrently. See Specifying the Number of CI DSPs in a C/I FSS Address Space for guidelines on setting values for this parameter.
- Use the MAXASST parameter to specify the maximum number of JCL statements all CI DSPs may process concurrently in this C/I FSS address space. See Selecting the address space JCL statement limit for guidelines on setting a value for this parameter.
For more information about coding the FSSDEF initialization statement and its selective parameters, see z/OS JES3 Initialization and Tuning Reference.