Dynamically allocating the IMSACBA and IMSACBB library data sets

Use the DFSMDA member with TYPE=IMSACBA and TYPE=IMSACBB to dynamically allocate the IMS IMSACBA and IMSACBB library data sets. Using DFSMDA to dynamically allocate IMSACBA and IMSACBB allows you to resize the inactive ACBLIB data sets, add data sets to the concatenation, or change data sets in the concatenation without bringing IMS down.

Restrictions:

Do not create database MDA members with a DDNAME=IMSACB.
Dynamic allocation statements for the ACBLIBA and ACBLIBB data sets can be combined in the same job. They cannot be combined with other statements to dynamically allocate any other IMS data set.

IMS dynamically allocates the IMS IMSACBA and IMSACBB library data sets with DISP=SHR.

To ensure that the IMS IMSACBA and IMSACBB library data sets can be dynamically allocated by your IMS control region, perform the following procedure:

Create DFSMDA members for the IMSACBA and IMSACBB library data sets. The following is a sample of the DFSMDA statements:

DFSMDA TYPE=INITIAL                                
DFSMDA TYPE=IMSACBA                                
DFSMDA TYPE=DATASET,DSNAME=IMSTESTL.ACB1           
DFSMDA TYPE=DATASET,DSNAME=IMSTESTL.ACB2           
DFSMDA TYPE=FINAL                                  
END                                                

DFSMDA TYPE=INITIAL                                
DFSMDA TYPE=IMSACBB                                
DFSMDA TYPE=DATASET,DSNAME=IMSTESTL.ACB3           
DFSMDA TYPE=DATASET,DSNAME=IMSTESTL.ACB4           
DFSMDA TYPE=FINAL                                  
END

Remove the IMSACBA and IMSACBB DD statements from your FDR, DBC, DCC, DLISAS, and IMS procedures. Sample JCL of the statements you should remove is shown below:
```
//IMSACBA DD DSN=IMSTESTL.ACB1,DISP=SHR
				DD DSN=IMSTESTL.ACB2,DISP=SHR
//IMSACBB DD DSN=IMSTESTL.ACB3,DISP=SHR
				DD DSN=IMSTESTL.ACB4,DISP=SHR
```
If you left in the IMSACBA and IMSACBB DD statements, they would take precedence over the DFSMDA member, and no dynamic allocation would occur.