The following guidelines will help you decide how much storage to request. Table 1 outlines the minimum amount of storage required for a request that includes information retrieval text units. You might want to obtain enough storage for all of your text units; if so, increase the amount of storage you request to accommodate your additional text units.
| Amount of storage (in bytes) | Purpose |
|---|---|
| 20 | Construct the RB (described in Setting up the request block) to submit your dynamic allocation request. |
| 36 | Construct the RBX (described in Setting up the request block extension) to use message processing and SJF information reason codes. |
| 4 per text unit | Construct the text unit pointer list with the addresses of your text units. Each text unit pointer is 4 bytes long. Multiply 4 times the number of text units to determine the amount of storage you need for the text unit pointer list. |
| 4 + (2 × number of text unit PARM fields) + (length of all text unit PARM fields) per information retrieval text unit | Construct your text unit (described in SVC 99 parameter list verb codes and text units, by function). For each information retrieval text unit, you will
need 4 bytes to contain:
For each information retrieval text unit, you require another 2 bytes to contain the length (LEN) of the parameter (PARM) field. If you code multiple PARM fields, you need 2 bytes for each PARM field you code. In addition, you need enough storage for the text unit PARMs. |