Extending the current size of a hiperspace

When you create a hiperspace and specify an initial size smaller than the maximum size, you can use DSPSERV EXTEND to increase the current size as your program uses more storage in the hiperspace. The BLOCKS parameter specifies the amount of storage you want to add to the current size of the hiperspace.

The system increases the hiperspace by the amount you specify, unless that amount would cause the system to exceed one of the following:

The hiperspace maximum size, as specified by the BLOCKS parameter on DSPSERV CREATE when the hiperspace was created
The installation limit for the combined total of data space and hiperspace storage with storage key 8 -F per address space. These limits are the system default or are set in the installation exit IEFUSI.

If one of those limits would be exceeded, the VAR parameter tells the system how to satisfy the EXTEND request.

VAR=YES (the variable request) tells the system to extend the hiperspace as much as possible without exceeding the limits set by the hiperspace maximum size or the installation limits. In other words, the system extends the hiperspace to one of the following sizes, depending on which is smaller:
- The maximum size specified on the BLOCKS parameter
- The largest size that would still keep the combined total of data space and hiperspace storage within the installation limit.
VAR=NO (the default) tells the system to:
- Abend the caller, if the extended size would exceed the maximum size
- Reject the request, if the hiperspace has storage key 8 - F and the request would exceed the installation limits.

For example, consider the hiperspace in Figure 1, where the current (and initial) size is 20,000 bytes and the maximum size is 100,000 bytes. If the creating program wanted to increase the current size to 50,000 bytes by adding a 30,000 bytes to the current size, it would code the following:

          DSPSERV EXTEND,STOKEN=HSSTOK,BLOCKS=HSBLCKS
          .
HSDELTA EQU  30000                   30000 BYTES OF SPACE
HSBLCKS DC   A((HSDELTA+4095)/4096)  NUMBER OF BLOCKS ADDED TO THE
*                                    HIPERSPACE
HSSTOK  DS  CL8                      STOKEN RETURNED FROM DSPSERV CREATE

The storage the program can use in the 100,000 byte hiperspace would then be the first 50,000 bytes, as shown in Figure 1:

Figure 1. Example of extending the current size of a hiperspace

This is an illustration of a Hiperspace with a current size of 50,000 bytes with arrows pointing up to show the remaining 50,000 bytes.

If you use VAR=YES when you issue the EXTEND request, use NUMBLKS to find out the size by which the system extended the hiperspace.