The lwIP stack provides different kinds of memories. Similarly, when the application uses socket mode, different memory options are used. All the configurable memory options are provided as a separate category. Default values work well unless application tuning is required. The following table describes the memory parameter options.
| Attribute | Default | Type | Description |
|---|---|---|---|
| mem_size | 131072 | Integer | Total size of the heap memory available, measured in bytes. For applications which use a lot of memory from heap (using C library malloc or lwIP routine mem_malloc or pbuf_alloc with PBUF_RAM option), this number should be made higher as per the requirements. |
| memp_n_pbuf | 16 | Integer | The number of memp struct pbufs. If the application sends a lot of data out of ROM (or other static memory), this should be set high. |
| memp_n_udp_pcb | 4 | Integer | The number of UDP protocol control blocks. One per active UDP connection. |
| memp_n_tcp_pcb | 32 | Integer | The number of simultaneously active TCP connections. |
| memp_n_tcp_pcb _listen | 8 | Integer | The number of listening TC connections. |
| memp_n_tcp_seg | 256 | Integer | The number of simultaneously queued TCP segments. |
| memp_n_sys_timeout | 8 | Integer | Number of simultaneously active timeouts. |
| memp_num_netbuf | 8 | Integer | Number of allowed structure instances of type netbufs. Applicable only in socket mode. |
| memp_num_netconn | 16 | Integer | Number of allowed structure instances of type netconns. Applicable only in socket mode. |
| memp_num_api_msg | 16 | Integer | Number of allowed structure instances of type api_msg. Applicable only in socket mode. |
| memp_num_tcpip_msg | 64 | Integer | Number of TCPIP msg structures (socket mode only). |
Note: Because Sockets Mode support uses Xilkernel services, the number of semaphores chosen in the Xilkernel configuration must take the value set for the memp_num_netbuf parameter into account. For FreeRTOS BSP there is no setting for the maximum number of semaphores. For FreeRTOS, you can create semaphores as long as memory is available.